These are very interesting photos! They appear to be wartime, 1941?..does someone have the gen on which year the London County Council registrations were please? Note left hand drive, civilian style front bumpers but military front end, and on the extreme left hand truck perhaps a twin rear wheel missing? They are apparently a gift from the USA so I am guessing 1941 Model YR if they have the 134" wheelbase. I have rego information on numerous YRs that were used for 'essential users' etc.
Note the very odd utility bodywork...this may have been by Duples and the fronts are similar to that of wartime utility buses.
Note also the difference in cowls between the two pairs of trucks...very odd!!