Since posting yesterday, I've exchanged a number of emails with the company I posted the link to.

The rifles they offer come from Germanyicon

Each rifle is made from a selection of parts from a variety of "Imperial" or Commonwealth "original spec" sources and some German engineered proprietary conversion/replacement parts.

So these are NOT individual rifles that have been converted.

They would be unable to supply a rifle that is completely made from a single original as this would have been originally classified as a Section 5 firearm and cannot therefore be re-worked to a Section 1 firearm (as per other posts above)

They would be unable to provide a rifle where all the original parts are from a UKicon manufacturer (although from different rifles).

When they refer to new "unissued" rifles on the website, these are made up the same way from unused parts of various origin. These are significantly more expensive than the refurbed/reconditioned used part models.

The rifles have been inspected by local police firearms officers (Met), that they carry german proof marks and that he would be prepared to have them re-proofed in the UK if asked. They also offer to supply "a formal note from the FSS that it is Section 1"....I guess this means Forensic Science Service?

I'm not sure if this is one of the above but I did find this during the course of my research.......if any body recognises themselves (or a friend?), I'd be interested in hearing about their experiences of the rifle shown and it's accuracy: