Initially the buses worked the
Maldon,
Braintree, and
Saffron Walden lines. They had too few seats for the Braintree branch and were used on the
Mildenhall line from July 1958. Mildenhall closed in 1962. E79961/3/4 had their Buessing engines replaced by
AEC A220X engines, also of 150 hp, in 1962–3, due to the cost of importing replacements from Germany. Their other branches closed in 1964, after which they spent most of their time in store at Cambridge. In 1965 79963 and 79964 were trialled on the
Alston Line, but couldn't haul parcels vans and had heating problems in winter. 79961 and 79964 were transferred to serve
Millers Dale in 1966, but that branch closed in 1967. M79961 was the last to be withdrawn in August 1967 ==Preservation==