Can you help to identify these frames, bikes or parts?

i have picked up a Dave Russell TT frame. it has mech hanger and track drop-outs. its a really beautiful frame. i feel its nicer than 531, but have no way of knowing...... how can i find out this information? who should i contact?

BB has serial number, first 2 letters are the original buyers initials
4 digits are the date stamp (year then month)
If it doesn't mention slough on the headtube badge it was made when he worked in Twyford.
There were also frames with 'DJR' rather than dave russell - these were bought in, but i'm guessing a supertoight TT frame would be a custom job.
I live near Slough, and IIRC Dave built wheels for Stowes (Windsor) so I can swing by and see if there's anyone there who's still in contact with his son, or knows much about the business/customers.
Hope this helps.