Having gone to Mole Valley Farmers to pick up sundries, including a can of wasp nest destroyer, I forgot it!
Never mind, Pauline (Pipley Court Alpacas) came to my rescue and gave me a can, so tonight at dusk, revenge was sweet, or so I hope, and the the deed was done. So, tomorrow I hope that on investigation I find a lot of dead wasp and we able to enter the barn without worry. On the other hand I might find that it didnt work and there are hundreds of very angry wasps with dreadful hangovers waiting to get their own back!