The Liberal brand is strong enough -the same applies to the larger two parties- that they can come back as long as they elect at least three MPs.
One MP doesn't work as the single MP is effectively an independent, see Douglas Carswell and Caroline Lucas. With two there is a problem if they are in opposing factions within the party, or one defects to one of the bigger parties. An interesting test case turns out to be the Canadian Progressive Conservatives, who did sort of but not quite came back from two MPs. The Scottish Nationalists and the Bloc Quebecois were both knocked down to two MPs at one point, we will see what happens with the Bloc.
The current Liberal Democrats are of course a good test case for this. But keep in mind that in the 1950s the Liberals weren't even running candidates in half of the constituencies.
One MP doesn't work as the single MP is effectively an independent, see Douglas Carswell and Caroline Lucas. With two there is a problem if they are in opposing factions within the party, or one defects to one of the bigger parties. An interesting test case turns out to be the Canadian Progressive Conservatives, who did sort of but not quite came back from two MPs. The Scottish Nationalists and the Bloc Quebecois were both knocked down to two MPs at one point, we will see what happens with the Bloc.
The current Liberal Democrats are of course a good test case for this. But keep in mind that in the 1950s the Liberals weren't even running candidates in half of the constituencies.