“In the UK, treaty-making is a matter for the Crown acting in conjunction with Parliament. The few instances of referendums and the like are insufficient to give rise to a constitutional convention saying that a referendum must be held if a treaty such as the European Union (EU) Reform Treaty is to be ratified. Whether or not there should be a referendum on the EU Reform Treaty is therefore a political rather than a legal question. This is except for the idea once floated by the Conservative Party of holding a referendum after ratification with a view to backing out of the Reform Treaty if it found against it, which does have legal implications. The professed purpose of such a post-ratification referendum is to engineer a breach by the UK of a legally binding promise that it had entered into freely and in accordance with domestic procedures and processes.”
Legal Week, 15th November 2007
Source: www.legalweek.com