London–Aylesbury line Aylesbury and by platform extensions up to Stoke Mandeville. In 1961 LT withdrew the Metropolitan line from Aylesbury and since then it goes only as far as Amersham. Following the end of steam-hauled Metropolitan line trains in 1961 the service was provided by British Rail Class 115 diesel multiple units until 1992 (which were then replaced by the line's current rolling stock) - along with Metropolitan line electric multiple units south of Amersham. Responsibility for the line north of Amersham was transferred from London Transport to British Railways on 11 September 1961; London Underground signage at the stations on this
London Underground infrastructure were originally maple wood, then aluminium from 1963, and this had been replaced with plastic or rubber following an increase in serious injuries following falls. However, following the King's Cross fire, aluminium treads have been used. There are 426 escalators on the London Underground system and the longest, at , is at Angel. The shortest, at Stratford, gives a vertical rise of . There are 184 lifts across the Underground, with 72 stations having step-free access from street to train. Major efforts have taken place to improve accessibility across the Underground, with the Jubilee line extension having lifts from opening