Thanks for your reply, I realise now my initial inquiry is misleading. I only covered the problem wires.As well as the slate black and the slate purple there are also three slate green (2 into one tag and one single tag) plus one slate.
Assuming the 3 slate green go to one post on the relay, this leaves the slate, slate black and slate purple.
The relay is from a late Mk2 manual overdrive which I have just scrapped and by the state of the outer cover it had never been disturbed but I assumed it works OK. The original XK150 relay had been tampered with in the past, hence the replacement, it also has one less post - C1 (double post) C2 and W1, which throws up more problems.
The loom was made to order by Autosparks who are very good and took all particulars of my XK before constructing it, I assume it is as good as possible. Very confusing!
As you have probably realised I am no electrician and there is no guide from the old wiring as it was rewired in the past in red and green wires only, with plenty of twisted connections with insulation tape (a complete rats nest).
Any further ideas would be most welcome. Many thanks. 3JagsPete