 The 6S units were intended to be introduced into service in June 1957 . On 5 April a fire at Cannon Street signal box disabled all signalling equipment there . As a result , locomotive @-@ hauled trains were banned from the station . A temporary signal box was commissioned on 5 May and the 6S units were introduced on peak services the next day . Two units coupled together formed the 06 : 58 and 07 : 26 Hastings – Cannon Street services in the morning , and the 17 : 18 and 18 : 03 Cannon Street – Hastings services in the evening . From 17 June the 6S and 6L units were working services throughout the day . The 6B units entered service between May and August 1958 . 
