THE prospect of all of Scotland's 59 MPs being barred from taking part in the 2015 General Election if voters say Yes to independence in the September referendum will be raised by peers with Nick Clegg tomorrow.

The Deputy Prime Minister will be grilled by the House of Lords Constitution Committee in his annual appearance before it as the UK Government's lead spokesman on constitutional matters and will be accompanied by Greg Clark, the Tory Cabinet Office Minister.

Among the questions Mr Clegg is expected to be asked is: would the UK Government's duty to represent the interests of Scotland continue to apply between the point of any Yes vote in the referendum and the day Scotland became an independent state and should Scottish MPs leave the House of Commons following any vote for independence?

Last month, John Stevenson, Tory MP for Carlisle, called for Scottish voters to be disenfranchised from the General Election if they voted Yes, warning that a potential constitutional crisis would loom if, having backed independence, they were allowed to vote at next May's poll, when they could determine which party would govern the UK if the vote were close.

Also tomorrow, Sir Nicholas Macpherson, Permanent Secretary to the Treasury, will be cross-examined by members of the House of Commons Public Administration Committee as part of their inquiry into civil service impartiality and the independence referendum.

Sir Nicholas was the mandarin who controversially advised George Osborne to rule out completely the SNP Government's key proposal of a currency union between an independent Scotland and the rest of the UK.

At the weekend, the Nationalists cried foul, claiming the lack of a paper trial for Sir Nicholas's advice suggested the Treasury position had been "cooked up" as a campaign tactic by Alistair Darling, leader of the Better Together campaign.

The Treasury dismissed the SNP's assertion as "nonsense" and branded it a tactic to divert voters' attention away from the fact there is no Plan B on what currency Scotland would use in the event of independence.