Researching the Nascom 2 computer, I found these schematics for the system. Interestingly, after the schematics for the computer itself, there is an added schematic for a disk controller to use with it. This schematic has a copyright statement describing it as owned by "Lucas Logic Limited", a company that I can find no references to in any of the Nascom related material I've looked at. I would assume that it was simply a third party adapter, except that the details on the schematic give an address for this company, and it is the same address (in Wedgenock Industrial Estate, Warwick, UK) that is widely published as the primary contact address for Nascom computers; it appears that Nascom was a trading name of Lucas Logic Ltd (although whether this was always the case I have been unable to ascertain).
Lucas Logic Limited was later renamed, and is currently called Artemis International Corporation Limited and apparently specialises in enterprise investment management software.
Lucas Logic's branding (visible in the schematics linked above) was similar to the current branding of automotive parts manufacturer Lucas Electrical, which like Lucas Logic is also based in the UK Midlands. But as of today, there doesn't appear to be any actual association between these entities. Is it known how they were related?