Since their formation, the Liberal Democrats have held every Lib Dem seat contested at a by-election, of which there have been 3. Including their successor parties, their most recent by-election loss was the 1982 Mitcham and Morden by-election, lost by the SDP ago. The SDP candidate had however defected from Labour – the last seat lost by either party that had been won at a previous election was the 1957 Carmarthen by-election, lost by the Liberals ago. Since 1982, the Liberal Democrats and predecessors together have defended 4; since 1957 they have defended 5 seats.