Renzo Piano is still finalising designs for Europe’s tallest skyscraper nearly five years after it was approved, it emerged this week.

The Pritzker prize-winning architect’s scheme for the 66-storey Shard of Glass at London Bridge for Sellar Properties was waved through by then deputy prime minister John Prescott after a public inquiry in 2003. Demolition work on the complex South Bank site started last year.

But a spokesman for Southwark Council’s planning department revealed that a number of design changes — including a revamp of the “back pack”, the tower’s lower portion of office accommodation — were being tabled ahead of main contractor Mace’s start on site this September.

“The Shard’s has changed four times,” he said, “and it’s still got changes to come.

“Most recently, there have been some minor external design revisions — to the canopy, for example, and to the appearance of the columns on St Thomas Street. Internally, there have also been some floor specification changes.”

Project architect William Matthews confirmed the practice was adjusting the Shard’s design. “We have made a very subtle change, adjusting the angle of the “back pack” in relation to the tower,” he said.

n A dual tower scheme by Wilkinson Eyre, also located in Southwark near Blackfriars Bridge, has been called in for a public inquiry by communities secretary Hazel Blears. The project, 20 Blackfriars Road, is for developer Circleplane.