Sounds like somebody at Milners made a mistake not like them to not apologise. At least they sent the correct ones.
I notice the picture I posted has been taken down - someone at milners doesn't like the truth perhaps?
They did send the correct gaskets after an exchange of emails. I sourced some additional spare gaskets from www.auto-doc.fr
in case they messed me about.
Good quality, made in Poland, delivered from Autodoc the german parent company in Berlin and a third of the price of Milner's proper gaskets.
In case importing stuff from the UK becomes a problem after brexit I have been looking for spare parts suppliers in europe, like you I'm in france and we both know how awkward the french authorities can be if they put their mind to it.