Thank you all for the suggestions but they have all been tried and there are no visible leaks at all as I said.
The scuttle is totally clean because it was taken off to do the HBV. Everything that could be cleaned was.
The car does not steam up inside at all, only when we get in with wet clothes and that soon clears. The carpets, as said, are totally dry right down to the metal floor itself. We use rubber well mats in wet weather and dry any water off them with tissue straight away. The carpets are totally dry under them. In summer (?) we use fabric, not rubber, over mats as a grit protection for the original carpets.
The only other thing I can think of doing is to replace the heater hose's matrix ends, the plastic self locking thingys, with jubilee clips to make certain that the joints are secure.
I have just had another looky underneath and cannot see any evidence of leaks even though I put down some lengths of wallpaper so I could see it better when I had been out for a paper this morning and got the engine hot. The engine temp rarely goes over 85-90.
Haha, come on lads, go on say it, its just being like a 'she' - temperamental.
Joking aside, its issing me off and I am constantly biting my mans bum about it. Have some pity on him.
cristina