UK & World News
One-Year Countdown To UK General Election
The Parliamentary Archives are hidden away under high security, deep in the Palace of Westminster's Victoria Tower. There are more than three million historic records there, including hand-scribed parchments, hundreds of metres long.
I went to the archives under escort in search of one relatively modest document, a pamphlet printed on vellum entitled The Fixed Term Parliament's Act 2011.
The Act, which was brought in by the current Conservative-Liberal Democrat coalition government, set regulations for the first time on when elections had to take place. In doing so, it changed the face of British politics.
Until now calling a general election was in the gift of the incumbent prime minister, subject to rubber stamping by the monarch.
Prime ministers would seek advantage by calling a snap vote or going long, or opponents in parliament would scheme so they had no alternative but to go to the country.
Fixed-term parliaments have changed all that. It is still just possible that there can be an early election but it would take a full-scale political crisis with the final decision taken by parliamentary votes not an opportunistic prime minister.
So barring very dramatic developments we can now say that we know when the next election will be - Thursday, May 7, 2015 - exactly one year from today.
One consequence of this is that the election campaign has effectively started. MPs are spending less and less time in Westminster and more around the country canvassing for votes. Already the number of hours and days the Commons sits for and the amount of legislation passed are at record lows.
The parties are fighting hard; in part because there is all to play for. Expectations about how the public might vote in a year's time are exceptionally uncertain.
Even before we get to the General Election there are two big votes which are likely to affect its outcome. In the European Parliamentary Elections this autumn, UKIP is hoping to come first, establishing its claim to be a durable national political force.
Then there is the independence referendum in September. Should Scotland vote to leave the UK, all bets would be off about the next General Election.
The opinion polls aren't much help suggesting who is going to win in 2015 either.
Labour has been in the lead for most of this parliament, but mostly only in single figures of percentage. On past form that is not enough to be certain of victory especially at a time when Ed Miliband lags behind David Cameron on leadership ratings and Labour is behind the Conservatives on economic competence.
Academic observers say Labour's edge is largely down to disillusioned defectors who voted for the Lib Dems in 2010. Mr Miliband's hopes of getting to Number 10 depend largely on how many of this group stick with him in 2015.
Meanwhile Mr Cameron's number one worry is UKIP. The rising UK Independence Party has recruited more supporters from Conservative ranks than anywhere else. If Mr Cameron can't get most of them back he looks doomed.
Even with what seems certain to be a smaller share of the vote than last time, the Liberal Democrats are still hoping for an inconclusive election result which leaves their band of MPs holding the balance of power.
As the 365-day countdown to May 7 begins, we are promised 12 months of tense and hard-fought politics.