Sir Keir Starmer’s former chief of staff Morgan McSweeney has been summoned to appear before the Foreign Affairs Committee of MPs next Tuesday amid the Lord Peter Mandelson vetting scandal.

It is highly unusual for Downing Street chiefs of staff to appear before Commons committees even after they have left post.

McSweeney is to appear next Tuesday to respond to allegations that Downing Street put huge pressure on the civil service to approve his appointment as the UK’s ambassador to Washington.