Last night, I ploughed through the five online bookies that offer constituency betting - Ladbrokes, Victor Chandler, William Hill, Paddy Power and Sky bet - and compared the market (no further reference to meerkats or clicking noises will be made). I attach below the table that I produced, which sets out the best prices I found, with the overround percentage for each constituency given at the top.
I would claim that this was an altruistic activity, but I did this entirely for my own benefit. There will probably be some errors, since I did all of this manually, and if so, apologies in advance. Happy browsing.
I have identified 13 constituencies where there is an underround: Birmingham Hall Green, Birmingham Northfield, Birmingham Selly Oak, Dunfermline & West Fife, Eastbourne, Middlesbrough South & Cleveland, Norwich South, Oxford East, Reading West, Richmond Park, Westmorland & Lonsdale, Wiltshire North and York Outer. I suggest that each of these must be worth a punt of some sort, given that the odds are skewed in our favour. The right choice(s) will vary from constituency to constituency and each punter will of course have his or her own view on the right choice.