The managing director of First National Building Society's mortgage subsidiary in Britain has resigned from the company. The resignation of Mr Chris Heard from Mortgage Trust (MT) is the second defection in recent weeks from the top management team at the mutual society, which is preparing for conversion to a plc and a stock market flotation.

Mr Heard's resignation follows that of Mr Gerry Murphy, who was an executive director of the building society with responsibility for operations and was based at its Dublin headquarters. Mr Heard was based in MT headquarters in Epsom, England. The resignations, coming after the society announced its plan to become a publicly-quoted bank, have surprised the market.

A First National spokesman insisted that the parting was amicable. "Mr Heard wanted to move on after 11 years with Mortgage Trust," he said. He declined to comment on a suggestion that Mr Heard had sought appointment to the society board and resigned when this was rejected. Other sources speculated that there was a clash in management styles between Mr Heard and management at the Dublin headquarters.

In a statement, Mr Heard said that he had decided it was "time for me to move on". He was not available for comment yesterday. Mr Heard was one of the founders of Mortgage Trust, which was set up in 1986 as a centralised mortgage lender. He was appointed managing director when First National bought Mortgage Trust in 1995 for £20.5 million from a Swedish bank, SE-Banken, which was withdrawing from the British mortgage market.