Stimson has over 20 years financial services experience with roles at Lehman Brothers, GMAC-RFC and Checkmate Mortgages before it rebranded to Portillion.
He has now joined Platform as head of product management and will work alongside David Tweedy, director of Platform, and Lee Gladwell, the firm’s business development director.
He will be responsible for product and funding strategies including risk and capital management.
He will be joined by another appointment, John Kilgallon, who joins the senior management team as head of planning and proposition.
Kilgallon also more than 20 years within the financial services sector and his former roles include head of mortgages at Abbey and head of change management at Barclaycard Commercial.
He will be responsible for longer-term strategic development.
David Tweedy, director of Platform, says: “We are delighted to make these high calibre appointments.
“Platform’s new leadership team has a wealth of experience in the intermediary sector and will provide the strategic direction needed to grow our presence and brand in the market.”