Prevc said he had not held in-depth discussions with Shuttleworth over his role at Make. He said: "I'll be bringing a different angle to what Ken does. It's a chance for me to help start a practice with a different view of life. We're all going to muck in."
The news will come as a setback to Foster, who has already lost project directors Sean Affleck and Jason Parker to Shuttleworth.
Industry sources had long speculated that there was a rift between Shuttleworth and Foster. The two were reported to have fallen out over the interview Shuttleworth gave to Building last January, in which he discussed his role in some of the practice's most prestigious buildings.
It has yet to be confirmed who will take over any further work on Elephant & Castle. However, Prevc said the project had come to a natural ending after planning permission was secured from Southwark council.