Byfield joined Jersey based Stanley - which trades in rare signatures and other collectibles - back in 2010 and has since spearheaded the AIM firm’s acquisition strategy.
Notable purchases include the £1mln takeover of stamp specialist Murray Payne last year.
Prior to joining, he acted as executive chairman of Essentially Group, formerly AIM listed, from 2002 until the company was sold in October 2009.
A Jersey resident, he holds a variety of directorships including one with a Jersey Financial Services Commission regulated trust company.
Martin Bralsford, Stanley Gibbons’ chairman, thanked Byfield for his contribution.
“John has overseen an active acquisition policy which has seen the group develop its activities into the diversified company that you see today.
“The board would like to thank John for his contribution and hard work during that time."