Tell him if he's that worried Callum, that he should probably cancel you just to be on the safe side, as you dont wanna be responsible for any external damage to his property. Play it cool and i'm sure he'll day something like..."Oh there will be no need for that". Then you insist that you really meant what you said, to which he will repeat what he said.....to which you end up with bumping the price up £20 as he's got you really concerned now
Oh if only i could practice what i preach