Editing LNER Class A4 (section)

==Post-war history==
[[File:Peterborough North 3 geograph-2284111-by-Ben-Brooksbank.jpg|thumb|No. 60034 ''[[LNER Class A4 60034 Lord Faringdon|Lord Faringdon]]'' hauling a train at [[Peterborough railway station]] in 1959.]]
Although newer Pacifics had been introduced since the war and the streamlined trains were never reinstated, the A4s continued on top link duties, notably on the London to Edinburgh services.

Even after the war was over, the A4s still continued to perform non-stop services. In August 1948, No. 60028 ''Walter K. Whigham'' managed to perform a non-stop service run from King's Cross to Edinburgh, setting the record for distance travelled for 408.65 miles. It would hold this record until No. 4472 ''Flying Scotsman'''s visit to Australia in 1988.<ref>{{cite web |last1=Marsden |first1=Richard |title=The Gresley A4 Pacifics |url=https://www.lner.info/locos/A/a4.php |website=LNER Encyclopedia |publisher=Winwaed Software Technology LLC |access-date=28 October 2020}}</ref>

Improved methods of aligning the Gresley conjugated valve gear in the 1950s led to tighter tolerances for the bearings used within it and, consequently, to almost total eradication of the overloading of the middle cylinder.{{Citation needed|date=December 2007}} History repeated itself with the inside big end being replaced by one of the Great Western type, after which there was no more trouble, provided that maintenance routines were respected.<ref>{{cite magazine |last1=Scott |first1=Ron |last2=Reed |first2=Brian |magazine=Loco Profile |issue=19 |title=Gresley A4s |publisher=Profile Publications |location=Berks UK |page=166 |year=1971 }}</ref>

The wholesale application of double Kylchap chimneys to the entire class was entirely due to the persistence of P.N. Townend, the Assistant Motive Power Superintendent at London King's Cross from 1956. He, at first, met with considerable resistance from higher authority. When permission was eventually given, it was found that the economy obtained over the single chimney A4s was from six to seven pounds of coal per mile, which more than justified the expense of the conversion.<ref>{{cite book |last=Rogers |first=Col. H.C.B. |title=Thompson & Peppercorn Locomotive Engineers |publisher=Ian Allan |location=London UK |year=1979 |isbn=0-7110-0910-4 |page=52}}</ref>

These improvements led to greatly increased availability.