On Monday, Paul Goodman set out ‘50 questions if Scotland votes Yes.’ In a piece for Prospect, Peter Riddell focuses on what could prove most the awkward of the lot:

“Of all the many uncertainties that would be created by a Scottish Yes vote on September 18th, none may be trickier than the position of Scottish MPs at Westminster. The challenges are both constitutional and political and could affect the legitimacy and viability of a UK government formed after next May’s general election.”

As Riddell points out, the Scottish MPs would have exactly the same rights after a Yes vote as before it:

“The referendum itself will in legal or constitutional terms not change the position of the 59 MPs from Scotland in Westminster at present. It starts a process of disengagement, and does not complete it. The MPs can only be removed by an act of the Westminster Parliament linked to the completion of a period of negotiations about how to separate Scotland from the present UK.”

Barring the unlikely scenario in which independence negotiations were concluded and legislated for before the next election, the next parliament will begin with 59 Scottish MPs still be sitting on the green benches with all their existing rights intact:

“A thorough report by the Lords Constitution Committee earlier this year said Scottish MPs should remain members of the Commons for as long as Scotland remains part of the UK. Until then, nothing would legally change and the Scottish MPs would be entitled to represent their constituents.”

This obviously has major implications for the legitimacy of the next government:

“…in only two general elections since 1945 would the largest party have been different if Scottish MPs had been excluded—1964 and February 1974. But, in October 1974 and 2010, Scottish MPs made the difference between a minority and a majority administration. The balance is all in one direction, benefiting Labour and working against the Conservatives.”

As various commentators have pointed out, the Conservatives could be the largest party in England, only to have Labour form the next government solely due to its soon-to-depart Scottish MPs. In fact, the numbers allow for an even more extreme scenario, in which the Conservatives hold an absolute majority of English, Welsh and Northern Irish seats, but Labour still ends up as the largest party in the Commons – again, courtesy of its Caledonian contingent.

So, let us imagine Ed Miliband in Downing Street with the most miserable of mandates. What happens next?

One can envisage an arrangement in which Scottish MPs agree not to vote on matters that pertain to England and Wales only. Even though this would render large parts of the Labour manifesto null and void, it is conceivable that Prime Minister Miliband would go along with it in the hope of winning a snap rUK election following Scotland’s final departure.

However, it’s more complicated than that. A Miliband government would, from the outset, have to make UK-wide decisions with post-independence consequences for England, Wales and Northern Ireland (for instance, Ed Balls’s first Budget or the terms of the independence agreement itself). Would Miliband really force through such measures using Scottish votes or would he do everything on the basis of cross-party agreements?

If he went for the latter option then he would be Prime Minister in name only. In the event that Labour might win a fresh set of rUK elections, Miliband would want to conclude the independence negotiations quickly, but that would allow both the SNP and the Conservatives to use delaying tactics to extract concessions. If, on the other hand, it was in Labour’s interest to delay before going to the country (or what remains of it), then Miliband would only be prolonging his impotent Premiership.

Of course, he might just go for the legitimacy-be-damned option and drive through his programme using Labour’s full Parliamentary strength. However, without a majority in the Lords, this might provoke the biggest bicameral bust-up since 1910.

I’ve far from exhausted the list of possible scenarios, but there aren’t many that don’t result in a full-blown constitutional crisis.