Jacqui,
This one struck a chord with me, but I may be leading you completely up the garden path as it were...
The question about Raleigh's numbering system 'stands' of course - but I have feeling the frame itself might be off-topic (but could be wrong).
I also have a Raleigh which has been 'rebranded' as a Bob Jackson. In my case I know the history, which is interesting.
Mine is the Lo-pro Raleigh Dynatech (big chunky lugs etc.,) that was made for Ian Cammish which he used to break the UK 100 mile record (and others) in the 1990s.
I bought it from the chap in Biggleswade who purchased it direct from Mr Cammish himself in Cambridgeshire - and it seems that when he parted company with Raleigh as a sponsor, he was allowed to keep the bike (and perhaps bikes plural?).
His next sponsor was Jacksons who resprayed the frame in pearlescent white and pink so it could be pressed into use for another season of racing.
It's a large frame - 24.5" (700c front and rear) and definitely a special build - though I can't find any frame no. on it so far...
...ring any bells with you? - perhaps yours is another frame made for him in a standard road geometry / config? - but just guessing.
On the other hand it might just be an 'ordinary' SB Raleigh that someone fancied dressing up as a Jackson.
Touch base with me off-list if you want any more info about my example.
Ian Briggs
LUTON UK