But what if the poll is as accurate as the Hartlepool one?

An opinion poll by NOP for ITV isuggests that Labour is on target to win back what was its safest seat in Wales – Blaenau Gwent – in the coming parliamentary by-election. Such a result would restore Labour’s Commons majority to what it was before the Dunfermline loss and ease some of the jitters within the party.

In a phone survey of with a sample of 1,000 NOP found the following shares LAB 47%: IND 35%: LD 6: PC 6%: CON 5

Labour lost the seat to Law in May 2005 (see pictures above) who stood as an independent in protest against the imposition of an all women short-list. His former agent is standing this time while his widow, Trish is running for his Welsh Assembly seat where the poll suggests that she is leading by 3%.

But opinion polls in Westminster by-elections do not have a good record – because it is very challenging measuring turn-out which is critical to the Labour vote in particular. Paty supporters have a long history of telling pollsters that they they will be voting – but then don’t.

The last NOP by-election poll at Hartlepool in September 2004 predicted that Labour would hold on with a massive 33% majority – they got in by 7%.

What might help Labour here is that supporters still sore by the short-list row might decide to “kick the party” in the Welsh Assembly vote by supporting Trish but stay loyal for the Westminster seat.

A worry for Labour campaigners is that the poll itself might induce a level of complacency which could lead to reduced turnout. It could also prompt those backing Law’s ex-agent to campaign even harder.

After that Hartlepool poll I suggested that Labour’s margin would be nowhere near what NOP was predicting – I believe the same will happen here and this race is much tighter than it might seem.

Betting on this by-election with Betfair has not really taken off yet and you can get 0.7/1 on Labour. The “any other party” option is even tighter at 0.67/1. The total a amount of matched bets is just £1,300 and there is no liquidity.

If the poll causes the “any other party” price to move out to 1.75/1 or longer then it might be worth a punt.

In the Bromley betting the Tories are 0.12/1 to retain the seat.

Mike Smithson