The lender has also promoted Mike Walters to head of sales within the division.
Sims has more than 20 years of experience in the mortgage industry, most recently as development director at HL Partnership and previously at Castle Trust among others.
UTB said Sims would be helping to define and implement its growth strategy and broadening distribution among networks, mortgage clubs and the direct adviser market.
Sims will be working within Walters’ team and closely with the commercial directors for the mortgages and bridging sections: Buster Tolfree and Gavin Diamond.
Walters will be predominantly responsible for increasing awareness and developing business volumes among brokers nationwide through an expanded team of business development managers (BDMs).
Paul Mansell, Nick Warren and Chris Pedlar were recently joined by Kerry Bradley and Paul Delmonte and together they provide sales support to brokers throughout England, Wales and Scotland.
Managing director for mortgages and bridging Robert Owen, said: “We are investing in technology to improve the broker experience and most importantly we are recruiting experienced industry professionals who can help us in the next exciting phase of the bank’s growth.
“We have made a significant impact on the specialist mortgage sector in a short time and Martin brings a wealth of knowledge to the team as we develop our relationships with networks, clubs and the DA market.
“Put that together with the expanded BDM presence under Mike’s leadership and we are looking forward to even greater success in the future,” he added.