On a happier note Martin, I've dug out that heater kit. It's still in it's original Smiths box and seems to have all the clips, connectors/wiring, fasteners, washers, airpipes, matrix/motor airbox, the whole lot as far as I can tell.
The only bad news is the mice have had a go at the instruction booklet but all the torn up bits are in there if you want a go at sticking it back together. Also I' assuming you've already got the brass tap which fixes to the cylinder head for the outflow feed?
I think I paid £50 for it, does that sound about right?