Davis-red, Cameron-blue, Rifkind-green, Clarke-black, Fox-pink

Has Cameron established himself as the clear challenger?

If the betting markets have got this right it looks as though the battle for the Tory leadership is now down to a straight fight between David David and David Cameron.

The Shadow Education Secretary has made some progress in the best betting prices following calls by his supporters for the other candidates to throw the towel in and support their man.

Even so the young Etonian at 7/1 has a long way to go before the markets think he can pose a serious challenge to David Davis who has seen his best bookmaker price tighten to 1/2.

Ken Clarke is still third place in the betting but his price has moved to 14/1 only slightly ahead of Sir Malcolm Rifkind and Liam Fox on 16/1.

The chart plots how sentiment is hardening behind the two Davids and it’s hard to see other candidates now gaining the traction to pose a serious threat to the front runners.

The real question is whether Cameron can now stop Davis.

A lot depends on how the two perform in the coming weeks. Will they try to support the party in the Cheadle by-election or will they keep away? How will they do in the Commons and how will they go down with the party at large? Cameron has come through this period well and might just be in with a chance although Davis does look very strong.

Mike Smithson