Editing GWR 2900 Class (section)

==Performance==
[[File:Swindon railway station geograph-2428215-by-Ben-Brooksbank.jpg|thumb| 2935 ''Caynham Court'' as rebuilt in 1931 with [[Lentz valve gear|Lentz]]-style rotary-cam [[poppet valve]]s, at Swindon 1946]]

The locomotives performed well as passenger locomotives over all the long-distance routes of the GWR and on all but the fastest express trains until they gradually became displaced to secondary services by the [[GWR 4073 Class|Castle Class]] in the late 1920s and 1930s.<ref>{{Cite book |last=Nock |first=Oswald Stevens |url=http://worldcat.org/oclc/11029500 |title=Great Western "Saint" class 4-6-0 |publisher=Patrick Stephens Ltd. |year=1983 |isbn=0-85059-632-7 |oclc=11029500}}</ref><ref>{{Cite book |last=Waters |first=Laurence |url=http://worldcat.org/oclc/972290341 |title=Great Western Saint Class Locomotives. |publisher=Pen and Sword |year=2017 |isbn=978-1-4738-5035-4 |oclc=972290341}}</ref> However, the {{convert|6|ft|8+1/2|in|m|3|abbr=on}} driving wheels limited their usefulness on freight trains. Churchward had recognized this limitation by the introduction of his [[GWR 4700 Class]] [[2-8-0]] design with {{convert|5|ft|8|in|m|3|abbr=on}} driving wheels in 1919, intended for express goods trains. However, Churchward's successor [[Charles Collett]] felt that a smaller-wheeled version of the 'Saint' class could form the basis of a successful [[mixed-traffic locomotive|mixed-traffic]] class of locomotives. He therefore rebuilt No. 2925 ''Saint Martin'' with {{convert|6|ft|m|3|abbr=on}} driving wheels to become the prototype of his successful [[GWR 4900 Class|Hall Class]] locomotives. Thus the 2900 class became a template for later GWR 2-cylinder 4-6-0 classes including the [[GWR 6959 Class|Modified Hall]], [[GWR 6800 Class|Grange]], [[GWR 7800 Class|Manor]] and [[GWR 1000 Class|County]] classes, all of which were of the same basic design.<ref name=RCTS5>{{harvnb |le Fleming|1953 |p=H4}}</ref> Moreover they also influenced similar engines on other railways such as the [[LMS Stanier Class 5 4-6-0|LMS "Black Fives"]], the [[LNER Thompson Class B1|LNER B1s]] and the [[BR Standard Class 5]]s.<ref name="Tuplin34">{{harvnb |Tuplin|1958 |p=H33}}</ref>

Collett also experimented on several other members of the class. In 1923 No. 2933 was given an altered [[blastpipe]] and in 1927 No. 2947 was fitted with cylinder by-pass valves. In 1931 No. 2935 was rebuilt with [[Lentz valve gear|Lentz]]-style [[Poppet valve|rotary cam poppet valve gear]],<ref name=RCTS4>{{harvnb |le Fleming|1953 |p=H25}}</ref> which remained in use until the engine was scrapped in 1948.<ref>{{cite web |title=A History of Lentz Valve Gear on British Steam Locomotives |url=https://www.lner.info/article/tech/valvegear/lentz.php |website=LNER Encyclopedia |access-date=22 March 2021}}</ref>