EPW056673 ENGLAND (1938). Thomas W. Ward Ltd Works, Silvertown, 1938

Definitely a 669 if the date of the photo is right. Route 669 running from Stratford Broadway -Canning Town was extended to North Woolwich from 5th February 1938. This route was joined by the 685, a daily service between The Crooked Billet (Walthamstow) and Canning Town, extended as a weekday peak service, initially to Silvertown, then further extended to North Woolwich, from 12th June 1939 (and 8th May 1940). Later these routes was joined by the 569, also a weekdays peak service, between Silvertown Station and Aldgate, from the 23rd July 1941.