I personally think these peope, would be ideal in a warzone. They can find the landmines.
However I don't believe it will be that hard to reduce all of this metal theft to an insignificant level.
I have seen no evidence that there is any organised crime involved here. It's just pikey scum and thicko chavs doing this. I beleive this is one of those rare cases where legislation is needed however all that is required is for it to be made suitable difficult for the thicko scum to be able to sell the stolen metal and it will stop.
As said aby a poster above, all scrap material bought needs to be forced to be paid for by bank transfer or similar means that requires a bank account. Even if teh scum manage to open an account, sell and empty it, once it is confirmed the person attached to that account sold stolen metal, the account can be frozen.
I'd imagine opening bank accounts with false details isn't that easy.