"Is there a guitarist in the UK who didn't have 'Play in a Day'?"

Sorry to say, but I'm one of the very few, it seems, who has never read (or even seen) the book, and learned to play guitar without its help.

Rather than use a tutor book, I taught myself to play in the early 1960s by playing along to all the latest releases (at the time!) from the Shadows, Beatles and Rolling Stones, so Bert's influence was obviously in there somewhere.

Yes, the world owes him a great debt of gratitude.