Came across these people recently:
The Electrical Parts Company Ltd
theelectricalpartscompanyltd.com/
They do exhibit at many of the shows, but I didn’t know until today that they supply the usual suspects with genuine parts (not Taiwanese copies).
They will also refurbish items like wiper motors etc.
They are happy to deal with joe-public, will take technical questions and offer advice.
There is no catalogue, so just ring up with the part number, or give the model and year and they will look it up.
They reckon to cover the entire Lucas range from the 1930’s to the early '70’s.
No connection etc. Must be worth a try for hard to obtain items, and certainly cheaper than via usual suspects.
Regards,
Stuart.