I could not find many streetcar stamps in my collection but this one may make up for that, featuring a Glasgow 'Coronation' Double Decker Tram No 1173 and a post box. The tram still exists and can be seen in the Glasgow Museum of Transport. This stamp was one of a set of 1988 for the Europa theme that year which the post office decided to feature Transport and Mail Services in the 1930s. The designer has used the style of the posters of the period that invited you to visit many parts of Britain travelling by train,
or in this poster of 1929 travel by tram, but why not give
Romania a try. A trolley bus from their series of definitives of the 1960s which featured different modes of transport and postal communications.
although I can never love a diesel train as much as a steam one
so here is a GB Maximum card featuring a 'King' Class loco the "King Edward I" climbing up to Whiteball Tunnel as it "heads the Plymouth-Taunton steam hauled section of a Pathfinder Tour charter train near Burlescombe". You can see the people on the train are doing what my mother always told me not to do and putting their heads out of the door and window. The stamp is of Great Western Railway's "King William IV" near Teignmouth in 1935, in the days when there were people in postal trains busy sorting mail through the night.