Everybody I know who has grown runner beans this year has had a problem with them not developing tinkertontom, so you are not alone. I have had about six beans despite the very prolific crop of flowers and I think the heat has been too much for them, even when they are watered well. Don't give up yet. If the weather gets a little cooler the remaining flowers may yet set and provide a crop.
As a matter of interest I have also grown purple podded climbing French beans (Thomson & Morgan) which have cropped excellently in the heat, and some Blue Lake variety climbing French beans which have also cropped well, so next year I'll stick to them and give the Runner Beans a miss in case we have another hot summer.