Partnership for Schools chief executive Tim Byles is to leave the schools delivery body to run his own firm, Construction Enquirer reported.
His departure adds to the turmoil surrounding the future of the government schools programme and raises fears that other key staff will leave, says Building.
The James Review into schools delivery, published last month after a five month delay, raised a question mark about the future role of PfS, calling for a new body with more far-reaching powers that would manage school building centrally as a means of driving down costs.
It is understood that Byles will establish his own company called Cornerstone that will look to buy public sector buildings and develop them for use in the education, healthcare and residential sectors - including as free schools.
Cornerstone is backed by John McDonough of Carillion and Rod Aldridge, founder of Capita, who also runs academy sponsor the Aldridge Foundation.
Byles said: “I have always believed in the value of delivering public services using the disciplines of the private sector and I look forward to developing that principle in my next venture, that will bring together the very best of the private, public and third sectors in a new breed of social investment company.”
Byles, who was widely credited with getting the Building School for the Future programme back on track after it was hit by serious delays several years ago, has led the schools delivery body since 2006.
Meanwhile, as the government considers its response to the James Review, PfS announced that £800m of work given the go-ahead will be let to the 15 contractors on its academies framework from June. The schemes will be divided into £250m worth of work in the North, and £550m worth in the South.
Altogether work will begin on eighty academies, including eight free schools which are being procured through the deal.