Sir Keir Starmer's rattled allies today issued a desperate warning to rebel Labour MPs that a leadership coup by Angela Rayner will trigger a general election. The under-fire Prime Minister is battling to stay in Downing Street as he reels from the Lord Mandelson scandal, with a number of backbenchers openly questioning his future. In a bid to contain the crisis, Sir Keir has promised to release documents related to Lord Mandelson's appointment as US ambassador in February last year. But the Government was forced into ceding control of the release of material to Parliament's Intelligence and Security Committee (ISC),...