Keep the roof wet.
Move to Wales even wetter here, although saying that the sun is shining here at this moment!You must be used to that in Manchester!
You could consider a shotgun but I dare say it would mess up the fabric in the process and blood is a bugger to get out of roof material.......................
are you speaking from experience jberks?
From experience, the only thing that works is to "educate" the cats with a decent water pistol (soaker). It doesn't harm the cat, but they absolutely hate getting wet. It may take a while for the message to sink-in but they get it in the end.....