Editing LNER Class A4 (section)

== Performance in service ==
No other British steam locomotives have a longer or more consistent record of high speed running than the A4s. Instances of 100&nbsp;mph running by them must exceed those of all other types combined,<ref>{{cite book |title=Locomotive Performance |first=R |last=Nelson |page=12}}</ref> though 90&nbsp;mph running was a relatively rare event with steam traction, much less 100&nbsp;mph. It should also be remembered that A4s operated on the East Coast Main Line which has more opportunities for high speed running (particularly Stoke Bank) than any other in the UK.
[[File:George Haygreen (left) on his retirement day with Charlie Fisher.jpg|thumb|George Henry Haygreen (left) on his retirement day with Fireman Charlie Fisher]]
In August 1936, the Silver Jubilee train on the descent of Stoke Bank headed by No. 2512 ''Silver Fox'' driven by George Henry Haygreen achieved a maximum of {{convert|113|mph|km/h|1|abbr=on}}, then the highest speed attained in Britain with an ordinary passenger train.<ref>{{cite book|last=Jones|first=Robin|title=Mallard 75|year=2013|publisher=Mortons Media Group Ltd|location=Horncastle|isbn=978-1-909128-15-6|page=54}}</ref> 
The fastest recorded post-war speed with British steam was also recorded by an A4. This occurred on 23 May 1959 on the Stephenson Locomotive Society Golden Jubilee special when No. 60007 ''Sir Nigel Gresley'' achieved 112&nbsp;mph when hauling 400 tons down Stoke Bank. The driver, Bill Hoole, had hoped for an attempt to beat Mallard's record, but [[Alan Pegler]], who was on the footplate and mindful of the risks, told him to ease off.{{r|Speed|pp=90–92}}

Although A4s were primarily designed for high speed express work they were also capable of high power outputs. In 1940, 4901 ''Capercaillie'' exerted 2,200 [[Horsepower#Drawbar power|drawbar horsepower]] on the straight and level track north of York when hauling 21 coaches (730 tons gross) at an average of 75.9&nbsp;mph for 25 miles.{{r|Allen|p=153}} On W.A. Tuplin's method for grading steam locomotive performance based on both power output and duration of effort, this was the highest value ever achieved by any British locomotive, at Grade 26.<ref>{{cite book |title=British Steam since 1900 |first1=W.A |last1=Tuplin |first2=George |last2=Allen |publisher=Unwin / Pan Books}}{{page needed|date=March 2019}}</ref>

The highest recorded power output from an A4 was 2,450 drawbar horsepower when ''Mallard'' herself was hauling 11 coaches (390 tons tare, 415 tons gross) ''up'' Stoke Bank at a sustained 80&nbsp;mph in 1963.<ref>{{cite book |title=British Locomotives of the 20th Century vol 3: 1960–the present day |first=O.S. |last=Nock |pages=89–91 |author-link=O. S. Nock |year=1985 |publisher=Guild Publishing/Book Club Associates |location=London |id=CN9613 }}</ref> [[O. S. Nock]] thought this performance superior to Mallard's world record run in 1938. An A4 with the same load on a "good run" would be doing about 50 to 60&nbsp;mph at the summit of Stoke Bank. On a run on 8 September 1961 ''Mallard'' had its train travelling at 78&nbsp;mph.<ref>{{cite magazine |magazine=The Railway Magazine |date=July 2013 |pages=16–17 |title=Practice & Performance: New Light on ... ''Mallard'' the Magnificent |first=Keith |last=Farr |editor-last=Pigott |editor-first=Nick |editor-link=Nick Pigott |issn=0033-8923 |publisher=Mortons Media Group |location=Horncastle |volume=159 |issue=1347 }}</ref>