A bit of progress was made.

I went to the spares car and got the steering rack and brake caliper. I could only get the front section of the exhaust. I'd also noticed that the tyres on the spares car look to be in better condition than Baby Blue's. The middle and rear sections wouldn't separate despite my best efforts with the 2lb lump hammer and a couple of screwdrivers. I fitted the brake caliper on Baby Blue but the section of pipe that immediately joins to the caliper sheared. Fortunately I'd clamped the flexible hose with my Mole grips so there was virtually no fluid loss and the same part on the spares car is in good condition and can be used. I've not had to spend any money on any parts for Baby Blue but I'm sure that this state of affairs won't carry on for much longer.