C'est compliqué tout ça, mon vieux.
The French decree, dated 2003, states that orphan CofA aircraft, designed more than 40 years ago and whose production ended more than 25 years ago, are eligible for a CDNR. That is a moving target, while EASA has used fixed dates. I also believe that "conception d'origine" is a more flexible term than "initial design", and that may also have influenced the French interpretation of when the DR1050 concept originated. https://www.legifrance.gouv.fr/loda/id/ ... 000612889/
So, it seems to me that, true to form, the French have looked after their own and agreed a list of aircraft with EASA, which may, or may not, strictly comply with Annex 1. I think it can be assumed that an aircraft on that list, registered in the UK, is covered by the exemption.
If you want want me to ask the DGAC if the DR1050 is covered, I'll be pleased to do so, but you have to be prepared to take no for an answer.