The price on Tony Blair being Labour leader at the General election dropped nearly a third in the aftermath of yesterday’s press conference when he appeared to look unwell.

Prior to yesterday the Blair price had been trading at about 1.6. In the immediate period afterwards it went to touch 1.8 and has now settled down at about 1.68.

For those not familiar with this form of pricing it means that if you had £100 at 1.6 you would receive your stake back plus £60 if Tony Blair is still there at the General Election. When the market rose to 1.8 bets placed at that level would bring a return of £80 plus the stake if he was still there. So when we say the price moved by a third we mean that your winnings would be a third higher.

Inevitably this sort of market is going to focus on the health of the leaders involved as well as the politics. In addition the “Still Party Leaders” market which lists a number of options that were relevant in October 2003 also saw some movement.

The most stable party leader market is on Michael Howard although you can still get 1.1 which seems good value given there is almost no political risk. Thus if you bet £100 you would receive £110 back, including your stake, at the General Election.