Pipisme has a superb TL detailing the Liberals' survival as the major party on the centre-left opposed to the Tories post-1923. The Liberal reforms of 1906 marked the end of classical, Gladstonian liberalism in the party and they transformed into progressive centre-leftists. What POD would be required for the Liberals to remain Gladstonian, or would it need to be a pre-1900 POD?