You make an offer and the vendor says "yes" or "no". If it has nearly sold 3 times with an asking price of £344k, my guess is that you are wasting your time offering anything less than £300k.
Any house that has been empty for a long period needs an internal inspection. It is quite possible that what was a perfectly good house a couple of years ago now needs a lot of work if, for example, lead has been stripped from the roof, copper water pipes have been removed causing flooding and, worst of all, if people have been burning the floorboards to keep warm while they inject.