Neither, says Dr Alun Wyburn-Powell, an honorary research fellow at the University of Leicester, on his blog. He dates the start of the Liberal revival to a deeply obscure by-election held in 1954:
The step change was the Inverness by-election of 21 December 1954 – neither famous nor a victory. The Liberals’ share of the vote at 36% gave them a very close second place to the winning Conservative candidate in this previously-Conservative held seat. The result was therefore not a dramatic upset. It took place in Scotland in the middle of winter and the results came out on Christmas Eve. Hardly surprisingly, not many people noticed. However, it was the Liberals’ highest share of the vote in a three-way by-election since 1932 and the improvement was sustained. In the 19 by-elections fought by all three major parties since the war leading up to Inverness the Liberals had averaged only 9.3% share of the vote, but in the 19 by-elections from Inverness onwards the Liberals averaged 25.2%.
Clement Davies, ageing and alcoholic party leader, had had a torrid time leading the Liberals through their darkest years, but in the last two years of his leadership the party averaged 26.5% in by-elections, but when Jo Grimond succeeded, the comparable figure for his first two years was slightly lower at 24.7%.Dr Wyburn-Powell specialises in Liberal history, so his blog is well worth following if you have an interest in that area.