 In the 1964 Government of Harold Wilson , Benn was Postmaster General , where he oversaw the opening of the Post Office Tower , then the UK 's tallest building , and the creations of the Post Bus service and Girobank . He proposed issuing stamps without the Sovereign 's head , but this met with private opposition from the Queen . Instead , the portrait was reduced to a small profile in silhouette , a format that is still used on commemorative stamps.f 
