In reply to Toby S:
I'd have to dig it out, but there is a good guide online somewhere to the Health & Safety responsibilities of a landlord (we had issues with a previous one). The basics were that it is their responsibility to ensure that the property is safe. If you can show that the burner wouldn't meet current regs, then they would be duty bound to sort it.
In reality, if your friend kicks up a fuss now, then they aren't likely to be offered tenancy. They could always ignore it now, and kick up a fuss when there is a contract. But then the easiest option would be for the landlord to release them early from it, and find someone who won't kick up a fuss.
That probably doesn't help...
Iain