That act is absolutely useless, scrapyards are still full of nicked scrap metal, Police and others will do nothing about it.
At least at work we get the odd member of the local itinerant population every now and then, turning the power back on whilst they are nicking it usually does the trick.. 🙂
Cordless angle grinders have been a boon for metal thieves, perhaps tithe sale of them should be made illegal.