There were a hell of a lot of good courses built (and remodeled) in the UK in the 20's and 30's. I would disagree with the assessment that things came to standstill after WWI.
Colt, Alison & Morrison were very active (MacKenzie was active in the early 20's as well), Fowler, Abercromby, Simpson & Croome; Hawtree & Taylor; Braid; Hutchison, Campbell & Hotchkin produced a number of top notch designs:
Sunningdale-New, Birkdale, Wentworth (36), Moor Park (54), Muirfield, Liphook, Ashridge, West Sussex, Berkshire (36), Boat of Garten, Deal, Saunton (36), Knole Park, North Foreland, Baltray, County Sligo, Tadmarton Heath, Trevose, Addington-New, Seaton Carew, Cavendish, Brancepth Castle, Manor House Hotel, Turnberry, Berkhamsted, Fulford Heath, Richmond Park, Addington Park, Longniddry, off the top of my head.
New Zealand, Hoylake, Cruden Bay, Ballybunion, Lytham & St. Annes, Worlington, Brora, Carnoustie, Rye were some of the courses redesigned during that period.
There was great deal of quality architecture taking place in the 20's and 30's.