Wales and Scotland have a plan to block a possible Westminster decision to leave the EU

The Welsh nationalist party, Plaid Cymru, revealed a plan drafted in conjunction with the SNP that could stop Britain from leaving the EU, even if the majority of England voted for it in a referendum. The plan would require such a decision to be unanimous among the four nations of the UK, by holding an independent referendum in each one. The Plaid Cymru leader, Leanne Wood, explained this morning to Sky News that "the votes in each of the nations should be added up separately and we should only pull out of the EU if all four countries want to do that".

The British Prime-Minister David Cameron has ruled out, last October, any possibility of different nations having an independent say over the overall decision, saying that a referendum would be decided based only on the majority of the people who vote. The leader of the Welsh nationalists went further and said she is prepared to submit an amendment to any referendum legislation requiring that "for the UK to leave the EU, each of the four constituent nations would have to vote to do so, not just the UK as whole."

This distinction is important because England has over 40 million people and the other three nations combined only about 8 million.

This would mean that if a UK-wide referendum is called, the interests of the three smaller constituents would have little impact when compared to England's views, where the Eurosceptic feelings are clearly more popular.

Ms Wood argues that "we have had a lot of talk during the Scottish referendum about the UK being a family of nations and all members of the family need to be involved in such a big decision". This plan would make sure that the interests of the three smaller members of the Union would be factored in by giving Wales, Scotland and Northern Ireland's population the possibility to veto an English decision to leave the EU.

Scottish nationalists leader Nicola Sturgeon supports the plan and has previously voiced similar views saying, just last October, that the Scots would want their own say about Britain leaving the EU.

David Cameron has promised that if his Conservative Party wins the next general election, in May 2016, a referendum on Britain's European Union membership would be called by 2017.