THURSDAY will see a nation go to the polls faced with the biggest question asked of an electorate for many a year: Do they wish to break a 300 year old marriage and go it alone?.
There is no doubt the referendum on Scottish independence has been a good thing, it has energised people and got a nation talking about politics and voting.
But whatever the result, this week marks the beginning of the end of David Cameron's time as Prime Minister. Quite simply, the leader of the Conservative and Unionist Party could oversee the end of the union, that's a mistake I doubt even he can come back from.
Perhaps reports of his demise in the aftermath of a Yes vote are a little far-fetched, I doubt the British economy would sustain the news of Scottish independence and the resignation of a Prime Minister within 48 hours of each other!
But it would signal Cameron's time at the top was nearly over, the vultures are circling with Boris looking a shoo-in in Uxbridge and most of the cabinet are Osborne loyalists - leaving the PM with very few friends at the top.
Even Uncle Rupert appears lukewarm in backing the Tories with his hints that independence could be good for Scotland, knowing full well the damage a yes would cause to the Conservative Prime Minister.
David Cameron will become the first PM in history to lose not because the opposition was much more electable (Labour aren't) but because he's just made too many tactical errors.
1) He hasn't managed the coalition well.
Cameron needed Nick Clegg and the Liberal Democrats in 2010 but what he needed to do from the outset was make it clear, they contributed just 1/6th of the coalition Government and policy would be Conservative-driven.
Instead he has been in thrall to Clegg and let the junior partners get away with a number of statements such as their apparent u-turn on the Bedroom Tax. Instead of putting them on the spot and telling them to vote with their feet, knowing it would send them off the political cliff, he's allowed the Lib Dems the airwaves to try and rewrite history.
2) But ignored his party...
It's no co-incidence his party aren't happy. Conservative backbenchers wanted Tory rule after 13 years away, instead they got a Tory Government watered down with a bit of Lib Dem.
Many want to see him rule properly, but within 12 months the old rivalries spilled out and open rebellion ensured.
3) He shouldn't have introduced fixed term Parliaments
Fixed five year parliament has not worked, the party has begun it's last year of the current cycle with very little ideas, very little enthusiasm and with a reshuffle based on image not talent. Government's in this country only go into the fifth year in a desperate attempt to roll the dice and hope their fortunes change, look at Major in 92 and Brown in 2010.
Rather than five year fixed term, make it compulsory to hold an election every four years. The fortunes of the ruling party do rather improve at the end of four year cycles.
4) He ignored and then didn't grasp the UKIP threat
'Fruitcakes' and 'Loons' were the words used by the Prime Minister to describe Nigel Farage and UKIP....oh how he must regret that now.
Quite simply the PM and his party didn't recognise UKIP began hoovering up traditional Tory votes a long time ago. Farage represents the halcyon days of the Conservatives, big on business, tough on Europe and traditional British values.
He dismissed them until it was too late, now many have gone and won't come back but still Cameron and his team still disrespect UKIP. Cameron should get on the front foot, agree to the debates and agree to Farage taking part and use his considerable oratory skills to take UKIP apart.
If he carries on until May 2015 he will be a lame duck Prime Minister, propped up by a party facing disaster.
However, victory on Thursday could and maybe should be enough for him to change course, call an election and ask people the ultimate question: "Do you really want Ed Miliband as PM?"