Thanks once again Tim and Richard.
Going through the paperwork I have on the car I’ve found an old email address for Allan Ellingworth and have emailed him. If I don’t get a reply I’ll come back to you as the address may be an old one. Also googled the reg number and found pictures of it on the run in Cornwall and at John O’Groats. Should have thought of that before 🙄. Now I just need to find some of its history from the Isle of Man where it was first registered!