The chairman of £655bn investment giant Standard Life Aberdeen has come under fire from an influential shareholder advisory group over an external post he holds at Big Four accountant Deloitte.

Pensions & Investment Research Consultants, which advises large investors such as pension funds on how to vote at annual general meetings, says a potential “conflict of interest” exists between Sir Gerry Grimstone’s position at the Scottish asset manager and his non-executive director role at Deloitte.