Hi all,
Had some interesting feedback from A Raleigh bike forum expert. It would appear that the bike was possibly a custom build for a specific customer - I've been told it could have even been made as a one off special for someone close to the Raleigh sbdu workshop.... Looks like it definitely isn't a mixed bag of parts, which does fall in line with what I know of its history so far.
I'm going to do a bit more investigation into how the family came to own the bike twenty something years ago.
Its amazing how much information people know on these forums!
Thanks.