John McFarlane, who for the last two years has been on a mission to turn the insurer Aviva into a "leaner more agile beast," is to take the chairmanship at Barclays – itself in the throes of shrinking its investment bank.

McFarlane is currently chairman of UK-listed insurer Aviva, where he has undertaken a root-and-branch review of the business since taking over in July 2012.