Kim Leadbeater and Sir Keir Starmer make speeches in Memorial Park, Cleckheaton, after Labour win the Batley and Spen by-election by a narrow margin of 323 votes.Asked what his message was to those still calling for a leadership challenge, Sir Keir said: “My message is, when the Labour Party sticks to its core values, is rooted in its communities and pulls together, we can win just as we have won here."