Editing LMS Coronation Class (section)

=== Modifications ===

==== Double chimneys ====
Single chimneys were fitted to Nos. 6220–6234 when built.{{r|Baker|p=59}} Following a successful trial using No. 6234 ''Duchess of Abercorn'' on 26 February 1939,{{r|Roden|pp=38–42}} these were replaced with [[double chimney|double blastpipes and chimney]]s between 1939 and 1944, the last being No. 6220 ''Coronation''. From No. 6235 onwards, all the locomotives were built with double blastpipes and chimneys.{{r|Baker|pp=59, 66}} {{r|Jenkinson|loc=Plate 77}}

==== Smoke deflectors ====
Following a report by George Ivatt in 1945, smoke deflectors were introduced due to drifting smoke obscuring the crew's forward vision.<ref name="Peacock"/>{{r|Roden|p=64}} The first locomotive to be fitted with smoke deflectors from the outset was No. 6253 ''City of St. Albans'' in September 1946. All the following four locomotives included this feature. The first unstreamlined locomotive to be retrofitted was No. 6232 ''Duchess of Montrose'' in February 1945.{{r|Baker|p=59}}

==== Removal of streamlining ====
George Ivatt's 1945 report also recommended the removal of all streamlining casings and they were removed from the fitted locomotives from 1946 onwards.{{r|Roden|p=64}} It had been found to be of little value at speeds below {{convert|90|mi/h|km/h|abbr=on}}, and was unpopular with running shed employees as it caused difficulty of access for maintenance. The first step towards de-streamlining was carried out during the Second World War when many of the streamlined tenders had their side sheets cut away at the rear of the tender. Many photographs exist showing this measure.{{r|Jenkinson|loc=Plates 34,96,114,125 and 144}}<ref name="Talbot11">{{cite book |last=Talbot |first=Edward |year=2011 |title=LMS POWER, The 'Coronation' Class |location=Stafford |publisher=Edward Talbot |isbn=978-0-9542787-5-5}}</ref>{{rp|pp=100–104 and 106 |at=Plates 147–150, 154–157 and 159}} The removal of the streamlining proper commenced in April 1946 with No. 6235 ''City of Birmingham''. All de-streamlining coincided with the fitting of smoke deflectors. No. 6243 ''City of Lancaster'' was renumbered as 46243 in April 1948{{r|Banks|p=148}} and, as it was not de-streamlined until May 1949, it became the only locomotive to carry its British Railways number while streamlined.

Initially, locomotives that had previously been streamlined could be readily recognised by the sloping top to the front of their smokeboxes, as well as slightly smaller front-facing cab windows.{{r|Baker|pp=56, 62}} {{r|Jenkinson|loc=Plate 86}} In due course all were re-equipped with cylindrical smokeboxes and larger cab windows, often, but not necessarily, at the same time.{{r|Jenkinson|loc=Plates 17, 41 and 127}}The first locomotive to receive a cylindrical smokebox was No. 6226 ''Duchess of Norfolk'' in October 1952. The last one to retain the sloping top was 46246 ''City of Manchester'' which appeared with its new smokebox in May 1960.{{r|Baker|p=59}}

Even following the conversion to cylindrical smokeboxes, it was still possible to distinguish some non-streamliners from ex-streamliners. On the former (Nos. 46230-46234 and 46249-46252, but not 46253-46257) the running plates veered downwards at right angles to connect with the buffer beam in the style of the Princess Royal Class.{{r|Jenkinson|loc=Plate 56}} The ex-streamliners did not have any such connection,{{r|Jenkinson|loc=Plate 3}} except No.46242 ''City of Glasgow'' which was rebuilt in 1952 following a serious collision.{{r|Jenkinson|loc=Plates 120 and 123}}

==== The final locomotives ====
The final two locomotives Nos. 6256 and 46257 ''Sir William A. Stanier, F.R.S'' and ''City of Salford'' were given many new features. In order to raise the mileage between general overhauls from 70,000 to 100,000, measures were taken to decrease wear to the axle bearings and [[hornguide]]s through the use of roller bearings and manganese steel linings. Other modifications included further superheating area, a redesigned rear frame and cast steel trailing truck, rocking grate, hopper ashpan and redesigned cab-sides.{{r|Roden|p=64}}{{r|Nock84|p=146}}

==== Automatic warning system ====
During the twentieth century, [[Signal passed at danger|signals passed at danger]] (SPADs) were increasingly perceived as a significant danger to the public. Only the [[Great Western Railway]] truly accepted the challenge posed. Prior even to 1910, it commenced installing [[Automatic Train Control]] (ATC), a system where each distant signal was accompanied by a ramp between the tracks with which a shoe on the locomotive would make contact as it passed over it. When the signal denoted "clear", an electric current would pass through the ramp which was detected by the shoe, thereby sounding a bell in the cab. With the signal at danger, the electric current would be cut off and when the shoe detected this it would activate a warning horn. In later forms, the brakes would be applied should the driver fail to acknowledge the warning.<ref>{{cite book |last=Rolt |first=L.T.C |author-link=L.T.C. Rolt |title=Red for Danger |edition=1st |year=1955 |publisher=The Bodley Head |location=London |pages=202–203}}</ref>

In 1952, the UK's most disastrous SPAD ever occurred at [[Harrow and Wealdstone rail crash|Harrow and Wealdstone]], in which No. 46242 ''City of Glasgow'' was severely damaged. The lack of an ATC system on most of Britain's railways was at last seen as an urgent issue. From 1956 the BR-designed [[Automatic Warning System]] (AWS) was installed. It was similar to ATC but relied on an induced magnetic field rather than an electric current and featured a visual indicator in the cab. The receiving system was installed on the Coronation class locomotives from 1959 onwards. The outward evidence of on-board AWS comprised a protective shield behind the front screw coupling, a box to house the necessary batteries immediately in front of the cab on the right-hand side and a cylindrical vacuum reservoir above the right-hand running plate.{{r|Baker|p=69}}