 As developments on the line from Chalfont Road to Chesham took place , progress continued on the 16 @-@ mile ( 26 km ) cross @-@ Chiltern link between Chalfont and Aylesbury . On 1 September 1892 work was completed as far as a temporary station south of Aylesbury . ( The connection with the Aylesbury and Buckingham Railway — absorbed by the Metropolitan Railway in 1891 — was completed in late 1893 . From 1 January 1894 MR trains used the A & BR 's Aylesbury station , and the temporary station was abandoned . ) The line to Chesham became a branch line , generally operated by a shuttle service between Chalfont Road and Chesham , although some trains at peak periods continued to run between London and Chesham . The MR had bought a number of Metropolitan Railway C Class locomotives to replace the ageing A and B class engines , but these performed poorly on the London @-@ Aylesbury line and were soon replaced by the Metropolitan Railway D Class . As a consequence , the C class engines were often used on the Chesham shuttle services . 
