I really should have formally published the collated data I published on the forum many years ago, as that has the answer to what you are asking:Jonathan Rogers wrote: ↑Sun Jan 30, 2022 12:30 pmI don't know - I'd like to know the ages of McNab, Levitt, Kosten, Davies, Arkell, maybe even Hebden, at the time they made their GM titles
Timeline of British Isles titles (1950-2010) (September 2010)
Ages when British Isles titles obtained (June 2011)
FIDE titles achieved by British Isles players since 2010 (May 2014)
As you will see, I tried to carefully define 'British Isles' to ensure the scope was clear. i.e. Including English, Scottish, Welsh, Irish and other relevant FIDE federation codes.
However, despite trying to keep the list updated, it proved difficult to keep it going, and the various "next GM" threads have been where the updates have tended to appear, though I see the most recent update to the 'FIDE titles achieved by British Isles players since 2010' thread was in 2021, so maybe an update is needed there for 2022 if someone is keeping track?