It occurs to me that a major reason why a Lab/Lib coalition was a complete non-starter is simply that it would not have commanded a majority of seats in England, and the regional parties it would have required for support don’t vote on England matters.
Hence, it couldn’t have passed any domestic English legislation without Tory support. Hence, it would immediately have collapsed, and hence, it could never have happened in the first place.
Take-out: the West Lothian question is self-resolving, and a de facto English parliament already exists: there is no conceivable scenario under which a party or alliance without a majority of English seats could govern the UK.
Sure, formally (or, more plausibly given the UK constitution, ‘creating a tradition of’) taking away Scottish, Welsh and Northern Irish MPs’ right to vote on laws that are solely domestic English in nature wouldn’t be a terrible thing to do. But it wouldn’t actually have any benefits for anybody, either…