Just to let people know, who may want to buy a copy of the DVD, that it is still available, however, if you visit the site using 'Firefox' browser, its security setting will block the site, but if you use Google Chrome or Microsoft Edge (or I presume any other Chromium based browser) you'll be able to access the site and order the DVD, even though the site is flagged as 'insecure' in the address bar, the PayPal checkout works OK and is fully secured.
John who owns the site is aware of the problem with the security settings on the site.
This is the direct link to the 'Codename R40' DVD:
http://www.bfcc.biz/triumphdvd/rover75.html
Steve