Referendum blocker

I thought other people might comment on this, but it seems obvious why arch Europhile Menzies Campbell has called for a referendum not on the new constitution, but on the very fact of our membership of the EU. It's because it allows the constitutional referendum to be opposed - No! We want a bigger, better referendum! - while calling for something that no main party is committed to and that no party would actually hold.

It's meant to be a killer blow to the idea of a constitutional referendum, and that's all.