For those who have puzzled over what make the top ball joints are from on the Ace Brooklands, I have now got the answer! I previously thought Jaguar and I can now confirm that they are off any of the following:
Jaguar / Daimler 420
XJ6 series one, two and three
Jaguar XJ-6
I now have the new one fitted without problem and a fresh MOT with no advisories!
As a further query, did anything come of producing a source list of parts for the Ace Brooklands? Unless one is produced soon, the relevant knowledge will disappear forever and the very existence of our cars will be in jeopardy!