A second referendum will take well over a year to organise, according to official guidance drawn up by civil servants in the Cabinet Office.

The guidance - leaked to Telegraph - was handed to MPs by David Lidington, Theresa May's effective deputy, at a meeting today in the Cabinet Office.

Three Liberal Democrat MPs - Alistair Carmichael, Jo Swinson and Tom Brake - were meeting Mr Lidington and Michael Gove, the Environment Secretary, in the Cabinet Office.

The guidance, pictured below, makes clear that at least 14 months will be needed to pass the legislation through Parliament and hold the second referendum which has been called for by campaigners.

This included passage of primary legislation (seven months), Electoral Commission question testing (12 weeks), passage of secondary legislation (six weeks) and designation of campaigns and the actual campaign (16 weeks).

Number 10 sources refused to say who had drawn up the document, but admitted it had been asked for by ministers.