How to fit Drayton Wiser smart TRVs on to old radiator valves?

[PurpleDino]

I moved into a new house and bought a Wiser Hub & smart TRVs, having use them before. I had the hub connected to the boiler but when I tried to fit the TRVs they don't fit to the existing valves- the metal ring nut is a mm or two too big. I contacted Wiser with photos who said they didn't know what sort of valves I had.
Please can someone help ID these valves, and for bonus points, advise how I get the smart TRVs to fit? [Someone suggested I was going to have to get them all changed to new ones, which is going to cost more than the Wiser kit did!].

Thank you