Hello dof. Just seen your 2018 (!) question. Shame nobody has thought to reply before, but here goes.
I have no idea whether there are any other RM owners who are members of the Riley Motor Club living in the Guildford area, but, if you were to join the Riley RM Club as well as the Riley Motor Club you would have access to both. The RM Club is devoted to the RM series only, if you join the RM Club and sign up for inclusion on the Membership List, you will have access to a full list of members in all parts of the country, as well as to the world beating Spares organisation, and a vibrant, helpfull Forum.
Hi. Yes, I am a member of both Clubs. I presume you have an RM! where are you? If you too are looking for RM contacts I may be able to help, although, obviously, there is little personal contact at the moment. I am in SE Cornwall.
Sorry my reply took so long, I do not regilarly check this forum as there is rarely very much 'action'.