Thanks for your reply.
From what I can gather, this is more a precautionary measure than anything else. I believe a problem will only arise in the unlikely event the "live" wire become detached and touches the metal bulb guard thus making it live (as there is no 'earth' attached for the current to return to ground). This seems to me very unlikely to happen (although not impossible!) but I just wondered what other people do? I'm hoping there must be plenty of people on here who have wired up their own basking lamps?.......
I'm not sure if the chap I've been speaking to is going really over-the-top safety wise or if there is a genuine cause for concern!