In what way was that a promise? The Conservatives clearly intended to hold a referendum (they had campaigned on it in 2010 but weren't able to get support from

In what way was that a promise? The Conservatives clearly intended to hold a referendum (they had campaigned on it in 2010 but weren't able to get support from the Lib Dems) so future membership was already in question - although voting Yes would have meant Scotland's exit anyway.