Thanks Guillaume, they both look good with #456 much more expensive than #415, but with one owner, reasonable mileage and enhancements; I believe.
Incidentally, if one follows your link to #456 it offers to translate the ad, in my case to English, and if one then scans the list of other bikes in the link, #415 is also there, with translated text; most helpful.
I am still looking, and discussing options but nothing final. Bridgland’s link to Pro Twins has been useful, and they have provided advice and suggestions to help with the search. So thanks also to Chris.
Importing a vehicle to UK from Europe, or elsewhere, has become more involved and expensive since Brexit. Without a Certificate of Conformity, because of bike’s age, support from DMH would almost certainly be needed to confirm the registration details to UK DVLA, and DMH usually ask for proof of ownership before providing the necessary information. Which is almost a Catch 22 situation, where one needs verification before purchase, to reduce transaction risk, but can’t obtain it until after purchase!
However, the search continues and all contributions are welcome.
Thanks again for the assistance so far, it is much appreciated.