In giving his go-ahead for the tower, Prescott said he concurred with the findings of his planning inspector John Gray, after the planning inquiry completed last May.
Gray cited several grounds for going ahead with the scheme. These were that the quality of the design made the building's unparalleled size acceptable, that the tower would not form a disruptive backdrop to St Paul's Cathedral when viewed from north London and that it would not harm the character or setting of the Tower of London.
This was in response to strong opposition by English Heritage, which was concerned about the building's height and the views of St Paul's and the Tower of London.
Fred Manson, former regeneration director of Southwark council, said that it was essential to have proper connections between the tower and the rebuilt station, particularly since the government had shelved its Thameslink rail improvement scheme, designed by TP Bennett.
"Network Rail has to understand that someone has to come up with a better scheme for the station, and Piano has done some attractive sketches," he said. "The interested parties should plan the right thing."