Under the terms of the deal, one of the largest in a decade if agreed, comprising more than 250,000 mortgage customers and £23bn of lending, Capita would take over The Co-operative Bank's mortgage servicing operations in Leek in Staffordshire and Plymouth, acquiring the people and assets of Western Mortgage Services Limited, the bank's mortgage administration business.

Around 660 people, technology systems and capabilities would be transferred to Capita, which will be supported by Unisys and Vertex Financial Services in the provision of servicing and mortgage origination platforms respectively.

Niall Booker, chief executive at The Co-operative Bank, says: "Our aim is to become a more efficient bank that is better placed to serve our individual and SME customers, with values and ethics at the heart of everything we do. It is vital we improve our processes, consolidate and utilise up to date mortgage systems and, as a smaller bank, ensure we can respond nimbly in a competitive market, mindful of the impact of increased regulation to our cost base."

Capita recently acquired Crown Mortgage Management (now Capita Mortgage Services) as part of a plan to expand its existing commercial debt serving capabilities and attract new business from the retail banking sector.

Capita chief Andy Parker, comments: "Capita would work with The Co-operative Bank to deliver an enhanced service for customers, by, for example, using analytics and insight to give them the experience they want and expect from their mortgage provider."

The deal and acquisition - subject to the approval of the board and regulatory bodies - is expected to take place in the first quarter of 2015.