"They couldn't possibly do that. Not even the Liberal Democrats could be in power in two places at once, in two different coalitions, with two different partners pursuing radically different policies."
Well seeing as I'm currently reading Micheal McManus's brilliant biography of Jo Grimond I know it is not a new argument. But I also know it is misconstrued.
For a start Lib Dems are in a devolved area of responsibility with a whole host of parties across the country in different council affiliations. The result is that not every council where the Lib Dems are the largest party or the smallest party can be accused of pursuing radically similar policies, that would be a nonsense. That is the result of coalitions, which if AV or a proportional election system were to come into Westminster would lead to more of the same; just like it always will do in Holyrood.
From history the Liberal party during the 60s were very careful to maintain their distinctiveness from the other parties when Wilson was having his shrinking majority issues. It is something that even today in Westminster we are determined to keep our Liberal identity. Today the Times [no links behind paywalls here] said that the Cabinet at Chequers today will rule out inviting prominent Conservative unto the Lib Dem Conference platform and vice versa. The reason being that the Lib Dems, in particular, were insistent that we must protect our separate identity. However, there will be crossover at fringe events, which as anyone who has ever attended a party conference will know is not something new or startling.
So it possible say yo be in power with the Tories in Westminster and Labour in Holyrood? I'd say yes. The one thing that the Liberal Democrats will do in either place to to bring our Liberal values to the fore. Yes there will be/have been compromise in both, but that is the nature of proportionality and power sharing.
The Liberal ethos is a mind set, listen into a debate at a Lib Dem conference and you will hear that coming to the fore. There are complexities within that mind set of course and while we do actually discuss our party policies it is always from the Liberal heart that binds us. Maybe that is something that is missing from the other parties' policy platforms. For the others here has been no tugging at the heart strings of members to come up with it, there is no ownership at grassroots level and there has been no debate cutting through to the crux of the matter.
That is why the Lib Dems can trust their elected representatives, they have sat in the hall, heard the party speak and know just what the party want. Therefore they can be trusted to make compromise in coalition that retains the identity of the party, it is also why I would trust a Lib Dem identity to be maintained in whatever formation we would end up supporting. Whereas a Labour or Tory seems willing to cut their heart out when it is convenient.