The 150m 2replacement, described as a 'folded metallic envelope', is triangular in shape and features a striking stainless-steel roof and a fully glazed frontage - a drastic departure from the existing circular facility.
Conservation watchdog the Twentieth Century Society is alarmed by the proposal, and is campaigning to have the existing pavilion relocated to Avoncroft Museum of Historic Buildings, Worcestershire.
Case worker Eva Branscome insisted the design, by Corporation of London architect Albert Richardson, is of tremendous historic importance and should be preserved.
'It is of obvious historic interest, being only one of three structures surviving from the Festival of Britain, next to the Royal Festival Hall on the South Bank and Lansbury Estate, Poplar,' Branscome said.
Defending the scheme, Make partner Sean Affleck said it would redefine the public space around St Paul's.
'This will be a simple, elegant, geometric form, not a pastiche. It will use modern construction techniques to ensure the design is environmentally friendly,' he said.
Planning approval is expected in June or July, with work on site beginning in October. The new kiosk is scheduled to open in April 2007.