Editing Chiltern Main Line (section)

==History==
===Early history and construction===
What is now the Chiltern Main Line was built in three key phases by the [[Great Western Railway]] (GWR) between 1852 and 1910:
* The first phase was the [[Birmingham and Oxford Junction Railway]] opened in 1852. The route ran from {{Stnlnk|London Paddington}} to Birmingham Snow Hill; in 1854, it was extended to [[Wolverhampton Low Level railway station|Wolverhampton Low Level]] and, connecting with other GWR lines, became the southern leg of a longer distance route to {{rws|Shrewsbury}}, {{rws|Chester}} and [[Birkenhead Woodside railway station|Birkenhead]]. It ran via the [[Great Western Main Line]] to {{stnlink|Didcot}} and then via {{Stnlnk|Oxford}}, {{rws|Banbury}} and Leamington Spa. This route was circuitous and was {{convert|16|mi|km}} longer between London and Birmingham than the rival [[London and North Western Railway]]'s [[Euston railway station|Euston]]-[[Birmingham New Street railway station|New Street]] route via {{rws|Rugby}}, meaning that the GWR could not compete on journey times.<ref>{{cite book |last=MacDermot |first=E.T.|year=1927 |title=History of the Great Western Railway, volume I 1833–1863 |location=London |publisher=Great Western Railway; Reprinted 1982, Ian Allan |isbn=0-7110-0411-0 |page=327, 336}}</ref><ref>{{cite book |last1=Boynton |first1=John |title=Main Line to Metro: Train and tram on the Great Western route: Birmingham Snow Hill – Wolverhampton |date=2001 |publisher=Mid England Books |isbn=978-0-9522248-9-1 |page=18}}</ref>
* The second phase was completed in 1906. In order to create a more direct route, the GWR collaborated with the [[Great Central Railway]] (GCR) to create a new railway known as the [[Great Western and Great Central Joint Railway]] between Northolt (in north-west London) and Ashendon Junction (west of [[Aylesbury]]) via {{rws|High Wycombe}}.<ref name="Jenkins">{{cite book |last=Jenkins |first=Stanley C. |title=The Great Western and Great Central Joint Railway |date=20 July 2006 |publisher=The Oakwood Press |isbn=9780853616535}}{{Page needed|date=May 2023}}</ref>
* Thirdly, as a final development, the GWR opened the ''Bicester cut-off line'' in 1910; this was an {{convert|18+1/4|mi|km|abbr=on}} connection between the Great Western and Great Central Joint Railway at Ashendon Junction, via {{rws|Bicester North}}, to Aynho Junction on the Birmingham line south of Banbury. This shortened the route between London and Birmingham by {{convert|18+1/2|mile|km}}, compared to the original Oxford route, and reduced the fastest London-Birmingham journey times by 20 minutes (from 140 to 120 minutes). Most of the through trains were immediately transferred to the new route, although the original route via Oxford continued in use and is now known as the [[Cherwell Valley line]].<ref name="Jenkins"/>
{{multiple image
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 | image1 = B&ojr.png
 | caption1 = The Birmingham and Oxford Junction Railway as built in 1852. Prior to the construction of the Bicester cut-off line in 1910, London to Birmingham trains had to run on the [[Cherwell Valley line|circuitous route]] via [[Oxford]].
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 | image2 = Gw&gc-overview.png
 | caption2 = The Great Western and Great Central Joint Railway (red) and the Bicester cut-off line (yellow) opened in 1906 and 1910 respectively. This completed the route of what is now the Chiltern Main Line.
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===GWR era===
Once the route between Birmingham and London was completed in 1852, the GWR introduced its first expresses between the two cities, timed at 2 hours 45 minutes, however this was soon revised to three hours, which matched the timings of the rival LNWR service. There was relatively little improvement for the rest of the 19th century, and three-hour expresses remained the standard timing of both companies until 1905, when the LNWR introduced new, more powerful [[LNWR Whale Precursor Class|Precursor Class]] locomotives, which allowed them to introduce two-hour expresses. The GWR could not compete with this, and it spurred the shortening of its route, as detailed above, which allowed them to introduce a matching timing of two hours once the works were completed in 1910.<ref>{{cite book |last1=Boynton |first1=John |title=Main Line to Metro: Train and tram on the Great Western route: Birmingham Snow Hill – Wolverhampton |date=2001 |publisher=Mid England Books |isbn=978-0-9522248-9-1 |pages=12-18}}</ref>

===Heyday, decline and rationalisation===
{{More citations needed section|date=June 2011}}
[[File:Seer Green geograph-2456422-by-Ben-Brooksbank.jpg|thumb|right|An ''Ex-''GWR [[GWR 6000 Class|King Class]] locomotive 6008 ''King James II'' hauling a Paddington to Birkenhead Woodside express in 1950]]
[[File:Seer Green station geograph-2400005-by-Ben-Brooksbank.jpg|thumb|right|A {{brc|52}} hauling an express from Paddington to Birkenhead Woodside near {{rws|Seer Green}} in 1962]]

During the heyday of the route, many prestigious trains ran from Paddington to the north-west of England, via the Joint Line; these reached Wolverhampton, {{rws|Shrewsbury}}, {{rws|Wrexham General}}, Chester and Birkenhead Woodside. Various through services from Marylebone to the GCR network also ran via the Joint Line between London and Ashendon Junction.

At [[Transport Act 1947|nationalisation in 1948]], the line passed to the [[Western Region of British Railways]], which continued to operate Paddington-Birmingham-Wolverhampton-Birkenhead fast trains through the 1950s in competition with the [[London Midland Region of British Railways|London Midland Region's]] (LMR) from Euston via the West Coast Main Line (WCML).

The Paddington-Birmingham-Wolverhampton-Birkenhead fast service was increased sharply in frequency to up to 15 trains a day each way from the 1959–60 timetable to compensate for the withdrawal of most London Midlands Region trains during electrification of the WCML.<ref>{{cite news |title=The winter timetables of British Railways: Western Region|work=[[Trains Illustrated]] |publisher=[[Ian Allan Publishing|Ian Allan]] |location=Hampton Court |date=December 1959 |page=584}}</ref> For the same reason, the Chiltern line was used by many trains between Paddington and Birkenhead from 1965.

All local trains were diverted to Marylebone in 1963 and operated by four-car [[British Rail Class 115|Class 115]] [[diesel multiple units]] (DMUs) and the main-line platforms at Greenford, on the New North route between Old Oak Common and Northolt Junction, were closed.

After the GCR main line was closed between {{rws|Calvert}} and {{rws|Rugby Central}} in September 1966, some trains from the South Coast were diverted north of Banbury via the route.  These became the forerunners of today's [[CrossCountry]] services between Birmingham and {{rws|Bournemouth}}.

[[File:Train, Marylebone station, London 3224106.jpg|thumb|right|Class 115 DMUs operated Marylebone – Banbury local services between 1960 and 1992]]

On 6 March 1967,<ref name=rcw>{{cite book |last=Collins |first=Paul|title=Rail Centres: Wolverhampton |publisher=Ian Allan |location=[[London]] |year=1990 |isbn=978-0-7110-1892-1}}</ref> after completion of the WCML electrification, express trains from Paddington to Birmingham/Wolverhampton/Birkenhead were discontinued under ''[[Beeching Axe|The Reshaping of British Railways]]''. The route was downgraded to secondary status, with all but one of the main-line services between London and Birmingham diverted via Oxford. In 1968, the line between Princes Risborough and Aynho Junction was reduced to single track and only a basic two-hourly DMU service between Marylebone and Banbury remained to serve Bicester.<ref name="BLHS">{{cite web |title=Railways |url=https://www.blhs.org.uk/index.php/transport/railways |publisher=Bicester Local History Society |access-date=21 October 2021}}</ref> Through lines were removed from most of those stations which had them, including Denham in 1965, Beaconsfield in 1973 and Gerrards Cross in 1989; the relief lines were lifted between Lapworth and Tyseley. The tunnel between Birmingham Moor Street and Snow Hill was closed on 2 March 1968.<ref name=rcw/> Local services from Leamington and Stratford terminated at Moor Street; the remaining services from Paddington and the South Coast were diverted into New Street. Snow Hill closed completely, along with most of the line to Wolverhampton, on 4 March 1972.<ref name=rcw/>

On 24 March 1974, the line from Marylebone to Banbury transferred from the Western Region to the [[London Midland Region of British Railways|London Midland Region]]; all stations between South Ruislip and Bicester were also transferred to LMR, giving LMR the responsibility of all passenger services out of Marylebone.

In 1977, the Parliamentary Select Committee on Nationalised Industries recommended considering [[Railway electrification in Great Britain|electrification of more of the rail network]] and, by 1979, BR presented a range of options to electrify numerous routes by 2000.<ref name="BR-CPU">{{cite book |author=Anonymous |title=Railway Electrification|date=Winter 1979 |publisher=[[British Railways Board]] (Central Publicity Unit) |pages=0–2, 8}}</ref> Some of these options included the Banbury–Birmingham section of the line, plus the [[Cherwell Valley Line]] and the [[Coventry to Leamington line]].<ref name="BR-CPU"/> Under the [[Premiership of Margaret Thatcher|1979–90 Conservative governments]] that succeeded the [[Callaghan ministry|1976–79 Labour government]], the proposals were not implemented.

The route was considered for partial closure between Marylebone and Northolt Junction in the early 1980s. All services would have run to Paddington, via the New North route; Marylebone station, and all lines leading to it, would have been closed and converted into a bus station. Services to and from Aylesbury would have been taken over by [[London Underground]] and run into [[Baker Street tube station|Baker Street]]. However, these proposals proved impractical and Marylebone was formally reprieved in 1986 (with a press announcement made on 30 April 1986) and the closure proposals rescinded.<ref name=Almostterminal>{{cite web |title=Almost Terminal: Marylebone's Brush With Destruction |url= http://www.londonreconnections.com/2014/near-terminal-case-saving-marylebone-rail-road-conversion/ |website=London Reconnections |access-date=15 September 2015 |date=20 February 2014}}</ref>

===Rejuvenation===
[[File:165027 at Kings Sutton.jpg|thumb|right|Class 165 DMUs were introduced to the Chiltern Main Line by Network SouthEast]]

With the sectorisation of British Rail in the mid-1980s, operations south of Banbury fell under the control of [[Network SouthEast]] in 1986, under the ''Thames & Chiltern'' sub-sector; this was split later into two constituent parts. In 1987, a new station was opened at [[Haddenham & Thame Parkway railway station|Haddenham & Thame Parkway]]. Birmingham Snow Hill reopened in 1987, on a much smaller scale than the original, beneath a [[multi-storey car park]]; its tunnel was reinstated and new platforms added to the through lines at Moor Street, where the terminus was taken out of use. Leamington/Stratford services were diverted to Snow Hill.

The opening of the extension of the parallel [[M40 motorway]] from Oxford to Birmingham in 1991 spawned development in towns along the northern section of the route, notably Bicester, Banbury, Leamington Spa and Warwick. This generated additional patronage for train services in the corridor.<ref name="OM">{{cite news |title= 100-year-old rail station steams into the future |url= https://www.oxfordmail.co.uk/news/8247619.100-year-old-rail-station-steams-future/ |work=Oxford Mail |access-date=21 October 2021 |date=1 July 2010}}</ref>

Between 1988 and 1992, British Rail used the Chiltern Line as a test bed for [[total route modernisation]]; this included resignalling from Marylebone to Aynho Junction, and both Marylebone to Aylesbury routes, from the new Marylebone [[Integrated Electronic Control Centre|Integrated Control Centre]], with full [[Automatic Train Protection]] provided. The track was renewed and Marylebone was refurbished. Much of this work was funded by selling part of Marylebone for development, which meant that the station lost two of its platforms; the central cab road at Marylebone was removed and two replacement platforms inserted in its place.<ref name=Almostterminal/> 

New {{brc|165}} ''Turbo'' trains were introduced in 1991, replacing the ageing 1960s diesels.<ref name=Almostterminal/> These improved passenger comfort and enabled journey times to be reduced; frequencies were increased, with an hourly stopping service to/from High Wycombe and hourly semi-fast service to/from Banbury. In 1993, Marylebone-Banbury services were extended to Snow Hill, calling at Leamington Spa, Warwick, Solihull and Moor Street, initially on a two-hourly frequency; these were increased to hourly in the following year. In 1995, the [[Birmingham to Worcester via Kidderminster Line|Jewellery Line]] was reopened, to allow Worcester line services to be diverted from New Street to Snow Hill; this resulted in some of Chiltern's weekday peak-period services to be extended beyond Snow Hill, first to Stourbridge Junction and then to Kidderminster.<ref>{{cite book |last1=Boynton |first1=John |title=Main Line to Metro: Train and tram on the Great Western route: Birmingham Snow Hill–Wolverhampton |date=2001 |publisher=Mid England Books |isbn=978-0-9522248-9-1 |page=70}}</ref>

===Chiltern Railways era===
Upon railway privatisation in 1996, the [[Chiltern Railways]] franchise was won by [[Chiltern Railways#History|M40 Trains]], a consortium of a management buyout, Laing Rail (a subsidiary of construction company and [[Private finance initiative|PFI]] specialist [[John Laing plc]]) and venture capitalist [[3i]]. In 1998, the line between Princes Risborough and Bicester North was redoubled by the company; this included the total reconstruction of [[Haddenham and Thame Parkway railway station|Haddenham and Thame Parkway]] at platform level, with two side platforms instead of the single platform constructed in 1987, and a new down platform at Princes Risborough, together with the raising of the speed limit. Also in 1998, the first Class 168 ''Clubman'' trains, with a maximum speed of {{convert|100|mph|kph|adj=on}}, were introduced to reduce journey times.

[[File:168107 A London Marylebone.JPG|thumb|right|upright=1.13|Chiltern Railways ordered 19 Class 168 DMUs for its Marylebone–Birmingham services]]

In 2000, Chiltern Railways opened a new station at [[Warwick Parkway railway station|Warwick Parkway]], to the west of the town next to the [[A46 road|A46]] and close to [[M40 motorway|M40]] Junction 15. This was intended to be a railhead for nearby towns without a station, such as [[Kenilworth]], and for towns south of Birmingham close to the [[M42 motorway|M42]] with no direct rail link to London, such as [[Redditch]] and [[Bromsgrove]]. Construction was funded by Chiltern Railways, with some support from [[Warwickshire County Council]]. At first, only Chiltern services called there but it is now also served by London Midland.

In 2002, after Chiltern won its 20-year [[exclusive right|franchise]], the line between Bicester North and Aynho Junction was also redoubled. Chiltern took over Hatton to Stratford-upon-Avon services from [[Thames Trains]] and [[Central Trains]], with direct services between Marylebone (rather than Paddington) and Stratford. Also at this time, Chiltern took over the operation of [[Leamington Spa railway station|Leamington Spa]], [[Warwick railway station|Warwick]], [[Hatton railway station (Warwickshire)|Hatton]] and [[Lapworth railway station|Lapworth]] stations from Central Trains, as the latter's services (now operated by London Midland) no longer operated beyond Dorridge except during weekday peak periods.

John Laing plc acquired 84% ownership of M40 Trains in 1999, buying out 3i; it was itself bought out by [[Henderson Group|Henderson Investments]] in 2006, resulting in the sale of Laing Rail to the German national railway operator [[Deutsche Bahn]] in 2007.

The [[Cherwell Valley]] line between Banbury and Leamington Spa was resignalled during 2004, with the closure of [[Fenny Compton]] signal box and the removal of its remaining semaphore signals. The new signalling and the existing signalling in the Leamington Spa station area is controlled from the box at Leamington via a new Westcad workstation.  More recently, the Leamington to Birmingham section has been resignalled and is controlled from the new [[West Midlands ICC]] at [[Saltley]] (taking over the old signalling centre at Saltley), with new 4-aspect LED signals throughout. But the manual signal boxes at Banbury North and South remained, along with some GWR lower-quadrant signals controlling the bay platforms and sidings at the station. In 2016, the station was remodelled and resignalled, being incorporated into the West Midlands ICC take over control as Oxford (exclusive) in 2016.<ref>{{cite web |url= https://www.networkrail.co.uk/feeds/orange-army-upgrades-railway-and-keeps-customers-moving-in-2016/ |title=Orange army upgrades railway and keeps customers moving in 2016 |publisher= Network Rail |access-date=19 May 2017 |date=2017 |archive-url= https://web.archive.org/web/20170402081301/https://www.networkrail.co.uk/feeds/orange-army-upgrades-railway-and-keeps-customers-moving-in-2016/ |archive-date=2 April 2017 |url-status=dead}}</ref>

Most of the route from Birmingham Snow Hill to Wolverhampton is now used by the [[Midland Metro]] light-rail system, which diverges from Network Rail's Jewellery Line at The Hawthorns.

The route between Marylebone and Leamington/Bordesley was used by [[open access operator]] [[Wrexham & Shropshire]]'s services from London to Wrexham, via Tame Bridge, Wolverhampton and Shrewsbury; this consisted of three [[British Rail Mark 3|Mark 3 coaches]], powered by [[British Rail Class 67|Class 67]] [[diesel locomotives]]. Since these were neither [[Sprinter (British Rail)|Sprinters]] nor [[InterCity 125|High Speed Trains]], they were restricted to lower line speeds, e.g. {{convert|60|mph|kph}} between Princes Risborough and Bicester, and {{convert|70|mph|kph}} between Leamington and Bordesley; they were permitted to travel at {{convert|85|mph|kph}} between Bicester and Aynho. Wrexham & Shropshire had negotiated with Network Rail to allow its trains to travel at higher speeds on these sections, which required it to show that they had sufficient brake force to stop from such speeds within the signal spacings.

Only the little-used line from Northolt Junction to Paddington has not been improved.

In September 2006, Chiltern completed its ''Evergreen 2'' upgrade project, carried out by [[Carillion]], which realigned the track through [[Beaconsfield railway station (Buckinghamshire)|Beaconsfield]] to increase non-stop speeds from {{convert|40|to|75|mph|kph}}, installed additional [[Railway signal|signals]] between High Wycombe and Bicester North and between Princes Risborough and Aylesbury, and added two platforms (Nos 5 and 6) at Marylebone, on the site of the daytime carriage sidings, replaced by the new Wembley Light Maintenance Depot, just south and west of [[Wembley Stadium station]]. The new platforms and partial resignalling of the station throat made it possible to run 20 trains per hour in and out of the station.

At weekends during 2008, when major engineering works were taking place on the WCML, the line was used by [[Virgin Trains]]' London Euston – {{Stnlnk|Birmingham International}} ''Blockade Buster'' service via Willesden, {{rws|Acton Main Line}}, {{rws|Ealing Broadway}}, {{rws|Greenford}}, High Wycombe, Banbury and {{rws|Coventry}}, using pairs of five-car Class 221 ''Super Voyager'' sets.