Isleworth had originally been Hounslow tram depot. It was rebuilt for trolleybuses in 1935. Unusually it operated just one route - the 657.
After the war Q1s were allocated but these were sold to Spain and replaced by older vehicles until closure in May 1962. The half reliefmodel is approx. 19" wide and 10" deep.
 
Note that the photos show the model with handmade non-operating overhead wiring..... which is not included!