Ohhh I feel just like whunter - using "answer" in the title.
But I do indeed have the answer to my question.
I've just spoken with a chap who relines these things for a living.
He seems to think that these brake bands are made of a paper based friction material. This paper based stuff is glued into place with a thermosetting lacquer. Apparently you need to be very quick when gluing it.
Whilst he says you might be able to get away with using a domestic oven as the curing temperature is at about 200 degrees C - I kind of think that the success rests on the word thermosetting...
See:-
http://en.wikipedia.org/wiki/Thermosetting_polymer
If you don't get the temperature right - well it probably won't be strong.
He reckons it would cost more to reline the old ones (if he was to do it) than it would be to buy the new ones. It is a labour intensive process - you pay more for the time than the stuff.
Although he didn't say it - he was far too polite - I need to stop being cheap.
{Even so if in the future I get on a brake lining course somewhere and I learn how to...}