The conjugated valve gear was tricky to maintain on the prototype, I understand?
The conjugated valve gear was fine as long as it received maintenance (according to Peter Townend) but problems arose, particularly during WW2 when high mileages accumulated between attention. Maintenance of any multi-cylinder loco will always be more awkward than a 2 cylinder arrangement. To be picky the Flaman speed recorder is incorrect for late crest A4s which had been equipped with Stones' speedos by that date.
Hugh
