There are tram or trolleybus wires on the overbridge passing the frame of the new Post Office exchange Believed to be 1956/57 Extract from The Post Office and Telegraph (Money) Bill, November 1955 “We plan a large increase in building starts in 1956–57. This will mean a start being made on 200 telephone buildings, mainly exchanges,.. I should add that within the next four years further automatic trunk exchanges will be brought into operation in ... Portsmouth”