Allotments 4 All

All the beans on one plant have turned out like this from bottom to top. They start of quite healthy looking, any ideas?

http://i158.photobucket.com/albums/t87/ninnyscrops/RBeans07.jpg

They look as though something's attacked them, though poor pollination also produces odd-shaped beans.

I thought slug or snail damage initially but the plants are quite close so can't understand why the beans from the adjoining plants haven't been attacked.  Could it be that I've planted a rogue seed with some kind of genetic disorder? (These were Scarlet Emporer saved seed.)

It looks as though a slug or snail has grazed along the beans, causing the distortion.  I have had a couple of cases this year where one runner plant has suffered severe damage right up the plant although its neighbours were not attacked.  In both cases the culprit was a large snail which had taken up residence high up the supporting cane and was simply working its way up the plant hidden under the foliage.

Thank you Kepouros - too late this year, but if it happens next year will be up there with a torch!  ;D