Oh, that sounds a bit depressing. As far as I could see, the problem is that the insulating panel has disintegrated and needs replacing and these still appear to be available from several suppliers. Hopefully, the metal plate/door to which it would be attached is OK. I am an eternal optimist.
Thanks Dan. I sent two images to admin for inclusion but last night I took a very powerful torch and shone it on the plate and everything was revealed: its a WM 552 OF. Oddly enough, by day and using the same torch the serviceman and I couldn't read a thing other than a production number.
I have a Baxi wall mounted conventional flu boiler which requires a heat exchange front plate but the registered serviceman cannot identify the model number as the indentification plate is worn, The boiler was installed about 22 years ago and the only number visible on the identity plate is...