Pat Bunton is stepping down as chairman of the Association of Mortgage Intermediaries (Ami), after leaving his role at London & Country.
Mr Bunton was operations and compliance director of London & Country, having joined in 1993. He is leaving to pursue other opportunities.
Robert Sinclair, chief executive of Ami, said the trade body's day-to-day work would continue through its employed executive team, and the board will now elect a new chairman.
London & Country will nominate a replacement to the board in due course.
Mr Sinclair said: "I have had the distinct pleasure of working alongside Pat as Ami chairman for just over five years.
"Pat has been a passionate advocate of consumer-focused advice and the role that advisers play in delivering great results to the UK population.
"He has given his time and considerable expertise and knowledge for no reward other than knowing he was doing the right thing.
"The intermediary sector owes him a great debt for the work he has done on the Mortgage Market Review, mortgage prisoners, the ongoing competition review, revision to the compensation scheme and a regulator that listens to the mortgage advice community.
"I would also like to thank the team at L&C who gave us Pat and his contribution without ever counting the many hours we took up."
Before joining L&C Mr Bunton held management roles at Britannia Building Society, while he has also been chairman of Oldfield Rugby Club since 1994.
