 By the mid @-@ 1950s , British Railways had begun to operate in regional units , and responsibility for services on the former Great Central routes in the Chilterns was transferred to the London Midland Region . Services on the branch were generally hauled by LMS Ivatt Class locomotives , although passenger trains continued to use the 1898 Ashbury cars . British Railways continued to operate goods services on the branch , although these declined steadily owing to competition from road haulage to the point at which coal deliveries were the only significant business . 
