IT merits just a couple of mentions in the SNP Government's White Paper, yet in the event of a Yes vote next September it could be the most critical event before independence day.

The 2015 General Election has been rather overlooked this week, but what happens in the run-up to the ballot and its outcome would have a fundamental impact on Scotland's exit deal, and hence the country's finances and economy.

The White Paper's references to 2015 are of the blink-and-you'll miss them variety. The first, point No. 542 in the Q&A section, says Scots voters would still elect MPs in 2015, but they would only sit until March 24, 2016.

After that, Scotland would be a sovereign state and Westminster would be a place of English, Welsh and Northern Ireland MPs only.

The second reference, point No. 546, asks whether the election would "prolong the timetable for negotiations" on Scotland leaving the UK.

The supremely bland answer supplied is: "There is no reason that it should do so. It will be in the interests of both countries to conclude the process in good time."

If only it were that simple. For, despite answer No. 546, the "countries" will not be concluding anything. The negotiations will be done by governments, and the distinction is crucial.

Because although the countries won't change, the 2015 election raises the prospect of Alex Salmond having to negotiate with not one Westminster government, but two. Two governments, two leaders, two attitudes, two sets of negotiating priorities. Which one would get the final say?

Would negotiations on the currency, Trident, the national debt and all the rest be conducted salami-style, each slice signed off in a rolling programme of talks? Or would it be one big package, agreed at the end of the SNP's 18-month timetable?

SNP sources are vague on the point, but reckon there might be a step-by-step sign off. Either way, if Ed Miliband replaces David Cameron in Downing Street, would he be bound to accept his predecessor's groundwork, or would he want to revisit it, arguing that he could do a better job than the Tory PM? If the latter, a change in government could make the first nine months of talks redundant, effectively halving the SNP's timetable.

At the very least, the General Election may create paralysis in Whitehall, as politicians and civil servants await the 2015 result.

Another aspect has been overlooked. If there is a Yes vote, the deal to be struck between Scotland and the rest of the UK (rUK) would become a political football for 2015. Of course, Labour, the LibDems, the Tories and Ukip wouldn't be so crass as to start a bidding war on who would be the most ruthless to the Scots. But it's not hard to imagine them saying they would maximise the deal for the RUK.

As to their old sister parties in Scotland, they wouldn't matter a damn, because the Scots MPs elected in 2015 would only have a nine-month shelf-life. If Miliband has to choose between playing to an rUK audience to secure long-term power or keeping Johann Lamont sweet, it's no contest.

True, Scotland would still be part of the UK during negotiations, so in theory a British PM would have a responsibility to cut a good deal for its citizens as well as those in rUK. But realpolitik means southern interests would immediately be prioritised by Westminster, because that's where the votes would be.

On Friday, Angus Robertson, the SNP's Westminster leader, said there was a "very good case" for delaying the General Election until 2016 because of the "very intense period of negotiation" after a Yes vote. "Perhaps being diverted by a General Election in the middle of that process is something one should be thinking about," he said.

He knows a Yes on September 18, 2014, would give May 7, 2015, a completely new complexion.