He joined the group in October 2010 as a non-executive director and became chairman in January 2011.
An ICAEW member and qualified barrister, he spent 30 years in investment banking with Schroders/Citigroup. He was formerly vice-chairman of Citi Europe and chairman of Citi’s European Investment Bank.
In a statement today, Swannell said “A year ago we chose Steve Rowe as our chief executive. Steve completed a thorough analysis of the business and developed a detailed plan to build a simpler and more relevant M&S.
“This plan is now underway and I feel that it is the right time for the business to look for a new chairman.
“It is a real privilege to chair this iconic company,” he added, “and I will continue to do so until my successor is in place.”
An experienced NED, he has also worked in government departments and with regulatory authorities. Appointments have included the Regulatory Decisions Committee of the Financial Services Authority, the Takeover Panel Appeal Board and the Industrial Development Advisory Board of the Department for Business, Energy and Industrial Strategy.