Managing director Andrew Bloom said: "This facility from RBS will enable MSL to compete strongly in the second charge sector, as we also continue to develop the wider Masthaven brand.
“A significant amount of hard work by both RBS and ourselves went into finalising this agreement.
“Having been the subject of a rigorous due diligence process, MSL is now in the fortunate position of being able to announce this funding line.
“I believe this will be the start of a highly positive step change in our ability to provide our introducers with not only a great service they have come to expect from us but also the kind of products which will make us even more competitive in this important sector."
Rob Jenkins, director, portfolio management, RBS, said: "Masthaven is already an established lender in the second charge mortgage market and RBS is delighted to provide them with their first bank funding line.
“We look forward to working closely with Andrew and the rest of the management team in helping the business achieve its future growth plans."
Nick Parkhouse, senior director, structured finance, RBS, added: “The team here at RBS has a great deal of experience lending into the secured loan market and we are especially pleased to provide facilities to support the on-going success of Masthaven."