As the Conservatives are well aware, 18 years have passed since the party won a general election.
Interestingly, it has also been 18 years since an election was fought in an even-numbered calendar year.
And all three of new Labours victories occurred in odd ones.
One of the beauties of our lack of fixed term parliaments is that elections can take place in any calendar year.
Given that we are currently in the neatly numbered 2010, what does that spell for the polls next week?
Well, of the 17 national votes since 1945 (including the 1974 double whammy) ten took place in odd years.
The bad news for the Conservatives is that historically they have not done well in even years, triumphing only in 1970 and 1992. Thatcher won her hat trick in odd-year votes, following a similar three-election run in the (odd) votes of the 1950s and 1960s.
Meanwhile, on balance Labour fare better in even numbered years, although it’s a close one at five even wins to four odd wins since 1945.
But that’s only half the story. Labour may win more often in even years, but they don’t do so decisively.
Only one even election – Harold Macmillan’s win in 1966 – saw Labour come out with a strong majority, compared with the sweeping victories of the Clement Atlee and Tony Blair odd year elections.
Not that even years give the Conservatives a decisive victory either. Both Ted Heath in 1970 and John Major in 1992 just scraped in with the largest share of seats.
So do even balanced years favour balanced parliaments? Keen observers may already have noticed that the last time Britain elected a hung parliament was in 1974.
Another even-numbered year.