Mandatory imposition of facial coverings in a liberal democracy is a big step and requires hard evidence to back it up. Enforcement by law as a possible psychological bromide really isn't a good enough reason (and could backfire). Like a lot of Conservatives, I'm queasy about it.

There are very good reasons to be sceptical, and this piece is worth a read.
The case for legal imposition (a significant step up from request, advise, etc) seems thin. https://www.spectator.co.uk/article/face-masks-should-there-be-a-cover-up-

(And if the reasoning behind all this is psychological, thanks but no thanks. I'd rather not go for a stroll around Waterstones with everyone dressed for the operating theatre.)