A planning submission will be submitted by next February following after architect BDP won the design race.

A winning contractor will be in place by August 2014 ready for work to start on site in 2015.

The scheme is scheduled to be completed by the end of 2016.

The county council wants to replace 12 out-of-town offices with a central base on Angel Street, which it claimed would save £54m in the long-run.

Northamptonshire County Council said 2,000 staff would work at the new office.

It added: “The design team will now develop their design before the procurement of the construction company.

“When the construction company is on board, a full business case will be prepared.”