Winston Churchill defected in his time, as did Oswald Mosley. In fact, a defection played a key part in the formation of the Conservative party.
The Labour split may cause electoral problems, but it could also prompt fresh thinking.
After voting no confidence in leader Jeremy Corbyn, angry MPs should think about forming an SDP-style alliance on the centre left.
Labour and the Conservatives have faced crises in the past… Just not at the same time.
Turmoil on the left led to a party split in 1983, and today’s circumstances look very familiar…