The Liberal Democrats are locked in a fierce political fight against Labour as they seek to win control of their fourth council in the capital.Party leader Sir Ed Davey joined activists in Merton, south-west London, as they focused on key wards in the borough which could decide who runs the council after May 7.In a wide-ranging interview ahead of the local elections, Sir Ed said his party was repelling the big squeeze on London politics by Zack Polanski’s Green Party and Nigel Farage’s Reform UK.