Im not saying there are refilling police but pointing out what happens when it all goes wrong. If you use refillable cylenders then they are given annual pressure test certificates for each cylinder and if its for air no test ticket no fills. same for acetylene cyls, boc have to carry out tests on them. When you see what happens to a simple cylinder when it fails on air alone, the mind boggles if you do the same with propane. And if you say that the bit about the insurers not covering you, then Im afraid youre being rather naive as these institutions will do anything not to pay out, its in their nature and if they can find you at fault they will, as do car insurers who will refuse to pay out if you have modified your vehicle and failed to inform them of the changes, driving over the speed limit doesnt really apply to this discussion