The quick signing of the deal means the project can get underway next month and open seven months earlier than first expected in May 2013.
Simon Walkley, Buckingham Rail Director, said: “As a local company we are especially pleased to have this opportunity to work with Warwickshire County Council on this exciting and challenging project.
The site chosen for the new station is at Bishopton, near the M40, and next to an existing park-and-ride facility.
Cllr Peter Butlin, the council’s Portfolio Holder for Highways and Transport, said: “This appointment of the contractor is giant step forward in the development of Stratford Parkway Station, and will mean that we can press ahead and look to open seven months ahead of schedule.