The idea is that if Prime Minister David Cameron fails to win the May 2015 general election, then Conservative MPs oust him and Mayor of London Boris Johnson is parachuted in to a safe Conservative seat and then wins and becomes Conservative leader.
So, what is wrong with it? Like all careful plotting, it relies on a cast of tens of thousands knowing their role- constituents and Conservative party members alike.
Firstly, what does it mean to lose a general election? Or to fail to win?
Once upon a time, a single party would win over half the seats in the House of Commons and - incredible as this sounds - Governments would be made up of politicians from just one party. It was immediately obvious who had won and who had lost.
But now? Did Cameron lost the May 2010 general election? He did form a Government comprised of his own Conservatives and the Liberal Democrats. But what if Labour had won just a few more seats and the Conservatives were the largest party and a Labour/Liberal Democrat government had been formed? Would Cameron have lost?
There was a narrative that was common among the Conservatives in the wilderness years. And it can be summed up as:
Margaret Thatcher led us to landslide victories in June 1983 and June 1987. Then MPs knifed her in the back and John Major became Prime Minister and simply threw away a massive majority and led us to a huge defeat in May 1997.
The problem with that narrative is that there was an election between 1987 and 1997- that of April 1992. And look at the result of that:
* In August 1987 the Liberals and Social Democrats voted to merge, and the Liberal Democrats were formed in March 1988. 3 Social Democrat MPs - Rosie Barnes (Greenwich), John Cartwright (Woolwich) and David Owen (Plymouth Devonport) - chose not to join the Liberal Democrats. Owen retired at the 1992 election, while Barnes and Cartwright sought re-election, and neither faced a Liberal Democrat challenger. I have included them in the Liberal Democrat total
^ Compared to the combined Liberal and Social Democrat vote in 1987
A common explanation is that the Conservative vote held up fairly well, but Liberal and Social Democrat voters switching to Labour pushed plenty of Conservative seats into the Labour column.
Now consider if the changes in share of the vote were matched at the 2015 election, and we get Labour on 292, Conservatives on 290*, and the Liberal Democrats on 40.
[* The calculator gives 291 Conservative MPs, but this includes John Bercow, the Speaker of the House of Commons and MP for Buckingham]
When you remove the Deputy Speakers (2 Labour, 1 Conservative), you have the two main parties tie-ing on 290 MPs. A Conservative/Liberal Demcrat or a Labour/Liberal Democrat government are both possible.
So, the Conservative vote has held up and the sitting Government can continue. Has Cameron won or lost?
And what about if the Conservative vote increases, but a large voter switch from the Liberal Democrats to Labour means a Labour Government? Has Cameron lost then?
In hung parliament and coalition territory, the terms "win" and "lose" are a bit harder to define.
Secondly, it assumes that Johnson would, in the cold light of day, want to become Conservative leader. Just assume that Cameron has, by a commonly-accepted definition, lost, and Labour leader Ted Miliband is then Prime Minister. Would Johnson really want to throw away a third term in power for opposition? What would he really want to be from May 2016 to May 2020- Mayor of London or Leader of the Opposition?
Thirdly, to be a candidate for the Conservative leadership he would have to be an MP. There is a story I've heard - and maybe any Labour people reading this can confirm - that one resson Michael Foot resigned as Labour leader after the 1983 election so a leadership election was completed in October 1983 was that Tony Benn had lost his seat in 1983 and Foot wanted the leadership election to be in motion before Benn had the chance to get back into the House of Commons, so that Benn could not be a candidate.
A quick resignation by Cameron after the 2015 election could lead to the nominations closing while Johnson is in the middle of a by-election campaign.
Fourthly, the Conservative MPs might not be compliant. In the last 2 leadership elections, MPs have ensured that an obvious winner has not made the top 2 (Michael Portillo in 2001 and the Minister without Portfolio, Ken Clarke, in 2005) from whom the members chose the leader.
Fifthly, even if Johnson manages to be a candidate, and Conservative MPs let him through to the final round, there is no guarantee that the members would elect him.
Sixthly, in every constituency there is a group of awkward people. The Parliamentary Voting System & Constituencies Act 2011 has at its heart the idea that in every seat there should be a roughly equal number of awkward people. They are called voters and have an annoying habit of not doing what they are told. While powerful men and women can draw up great schemes, it's the voters who can - armed with no more than a pencil - destroy such a person's dreams and plans. The pen is indeed mightier than the sword.
The result in Blaenau Gwent at the May 2005 general election is a useful reminder of just how awkward these people can be.
Voters don't like being taken for granted. Just after the 1983 election, Thatcher appointed William Whitelaw to be Lord President of the Council and Leader of the House of Lords. Naturally enough, he had to leave the House of Commons and there was a by-election in his Penrith & the Border seat in July 1983, which saw David Maclean (later to be Conservative Chief Whip) win, but narrowly, as the Liberals nearly overturned a 30% majority.
Yes, they might find Johnson a safe seat. But Penrith & the Border was a safe seat. The voters don't like being used. Is someone really going to stand for re-election in 2015, promising to do the full 5 years, while deep down just keeping the seat warm until Johnson decides to stand? That would be treating their constituents with contempt.