I have now started work on this. The setting is the British Isles between 1914 and 1920, with a special concentration on the Celtic nations of Great Britain.
Don't get too excited too quickly. Only the first chapter of the first volume of the Trilogy is complete. It will be at least volume two before a Scottish dimension emerges and fans of militant Welshmen might have to wait even longer...
A long overdue update: I'm now just under 50,000 words in on volume one ( "A Nation Once Again" ) which should finally top 80,000 words. Volume two ( "Too Much England") exists in outline form and volume three (as yet untitled) is just a fifteen item list of chapter headings. Watch this space.......