The appointments follows the surprise departure of Stephan Ludwig and Ian Goldbart who, as reported in ATG earlier this month, both left parent company Stanley Gibbons last month.
During Ludwig's recent absence at Mallett's HQ in Dover Street, George Bailey, chairman of Dreweatts & Bloomsbury Auctions and founder of online firm The Auction Room, has been responsible for major decision making.
He will now work together with James Harvey and Thomas Woodham-Smith, who both become co-chief executives of The Fine Art Auction Group (TFAAG).
Stanley Gibbons chief executive Mike Hall informed staff of the changes in an email of October 22 seen by ATG.
Harvey, who spent almost 20 years sourcing and selling paintings for Mallett before setting up as James Harvey British & Sporting Art, was appointed international head of traditional art at Dreweatts & Bloomsbury last August.
According to Hall's email, he has now agreed to take on a broader management role.
Thomas Woodham-Smith returns to Mallett where he was a director until 2010. He was creative director at Masterpiece until 2013 and has latterly been dealing independently.
The new team comes together roughly two years after Stanley Gibbons acquired the Dreweatts group in November 2013.
A founding shareholder in The Fine Art Auction Group, Ludwig negotiated both the merger of Dreweatts and Bloomsbury Auctions in 2010 and the £8.6m purchase in 2014 of Mayfair dealership Mallett where he held the position of chief executive.
Integration of the auction and retail enterprises is now under way with Dreweatts-Bloomsbury using Ely House, Mallett's Dover Street showroom, as both an office space and a London sale venue.
Goldbart, a former stockbroker and coin collector, founded Noble Investments in 1993, acquiring numismatic specialists AH Baldwin in 2004 and The Fine Art Auction Group in December 2013.
ATG contacted Stanley Gibbons but no one was available to comment at the time of going to press.