Worldpay is owned by Advent International and Bain Capital, which are looking to list it on the London stock market, possibly later this year, and the appointment of Sir Mike will help that process, people familiar with the matter said.
The private equity firms bought Worldpay from Royal Bank of Scotland in 2010 for about £2bn and could sell it to another investor, but a listing is the preferred option, sources said.
Worldpay, which provides the platforms to allow merchants to accept payments by cards and other methods, would be one of Europe’s biggest listings in years.
The estimated £6bn valuation includes debt of about £2bn, so its market value could be nearer £4bn, enough to make it into the FTSE 100 blue-chip share index.
Private equity firms CVC and Hellman & Friedman are considering separate bids for Worldpay, sources said.
Sir Mike has been on Barclays’ board for seven years and its deputy chairman since July 2012. As its senior independent director he was a key figure in the abrupt removal of chief executive Antony Jenkins last week.
“It became clear to all of us that a new set of skills were required for the period ahead,” Sir Mike said in a statement when Mr Jenkins left, adding he discussed changing the CEO with other non-executives.
Barclays said Sir Mike intended to remain as its deputy chairman and senior independent director until at least the end of 2015.
He is also chairman of BT Group and investors typically ask people to “comply or explain” if they are chair of more than one major company.
Sir Mike is one of the City of London’s best-known businessmen. He spent more than 30 years with KPMG, where he was chairman of KPMG International and is a former president of the Confederation of British Industry and held several other senior roles in business, education and with charities, and advised the Prime Minister.
He will replace John Allan as Worldpay’s chairman. Mr Allan, who is also chairman of retailer Tesco, has said he would remain on its board.