Its chief executive Ian Balfour said the appointments were made to cope with more business, as its enquiry levels have risen every month this year.
Sadler has joined the Gosport-based distributor after spending the last seven years at Nationwide, while Thompson re-joined after leaving the business in 2008 when the credit crunch rocked the industry.
Balfour said: “I am delighted to welcome back Anna to SMS and welcome Clare to the team.
“Both of them are vastly experienced in our market and I know that our introducers will enjoy working with them.”
After starting out at Britannia Building Society, Sadler has gained underwriting experience with Preferred Mortgages, Mortgage plc and Advantage.
Thompson’s banking career started at Barclays, where she worked for nine years, before she spent a year with Abbey National.
She first joined SMS in June 2001 as team leader, while she re-joined from NCI Resources.