Editing Chiltern Main Line (section)

===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.