Coventry Building Society is to expand its headquarters in one of the biggest office lettings deals of the year.

The Coventry, the UK’s third largest building society, which merged with Stroud & Swindon Building Society earlier this year – is expanding operations to the Oak Tree Court building on the Binley Business Park after agreeing a new 15-year lease.

Up to 275 employees will be based at the 30,000 sq ft building which is currently the headquarters of the Coventry and Warwickshire Chamber of Commerce, after an off market deal was proposed and completed by commercial property specialists D&P Holt.

Under the deal, the Chamber will surrender its lease but will continue to occupy around 6,000 sq ft of the building.

Justin Quibell, from D&P Holt which acted on behalf of owners A&J Mucklow, said: “This deal is a boost for the office market in Coventry and Warwickshire demonstrating that deals are still there to be done and we are delighted to have completed the letting in a difficult but improving market.”

The building society currently occupies the 52,500 sq ft Oakfield House, also on the Binley Business Park.

The Birmingham Post reported in March that the Coventry’s merger with the Stroud & Swindon, then the UK’s 11th largest mutual, would create a combined group with around 1.5 million members and assets of around £21.1 billion.

The enlarged business has a combined network of 91 branches and agencies across the Midlands and South West.

The Coventry has since reported a rise in annual underlying pre-tax profits of 40 per cent, to £46.5 million.

Coventry Building Society’s agent for the Binley Business Park deal was Colliers International, while D&P Holt acted on behalf of landlords A&J Mucklow.