Well an evening with some tools resulted in very greasy hands and the following pile of bits:
Not shown are the handlebars, brakes and some other bits that I intend to reuse. The deraillieurs and down-tube shifters have no future use for me, but I’ll hang on to them in case I ever want to rebuild the bike as it was originally intended.
The wheels are 27” x 1 1⁄4 so it may be tricky getting new tyres for them, but hopefully online suppliers will still stock them.
Next job: cleaning everything up and taking stock of what I have