Could anyone (Probably Dan😉) add an alternative link...
I'll look into it directly, Mac. The Internet Archives are endangered and a number of older files, particularly PDFs are simply disappearing. There are a number or causes, from a targeted hack to copyright lawsuits. There are multiple major institutional backups, but accessing them from afar can be problematic. As soon as/if I can find it, I will post a link here, as chances are others may wish to see it too.
I've found the splash page for the 26in wheeled Mercury here...
https://web.archive.org/web/20070827164148if_/http://www.thorncycles.co.uk/mercury.html...but so far, the PDF links from that page are inaccessible.
In my own personal archives, I have the brochure for the 700C Mercury, but the 26in version is missing.
Will keep looking. If any members find it, please give a shout.
Nice to have you back, Mac!
All the best, Dan.