This photo shows STL 2377 (EGO 426) a 1937 AEC Regent I bus with London Passenger Transport Board 56-seater bodywork inside Romford Bus Garage where an Open Day was taking place. The advertisement on the side is for Hovis Bread whilst the two on the front on the bus are for the magazine Picture Post which came out between 1938 and 1957. This particular bus is kept in the London Bus Museum, further details being at <a rel="nofollow" class="external text" href="https://www.londonbusmuseum.com/museum-exhibits/double-deck-buses/aec-regent-i-stl-2377/">Link</a>.
<a rel="nofollow" class="external text" href="https://www.geograph.org.uk/profile/22410">David Hillas</a>
CC BY-SA 2.0
From <a rel="nofollow" class="external text" href="https://www.geograph.org.uk/photo/7475970">geograph.org.uk</a>