What's a good metric for when to stop masking?

In common with most people in the UK, I downed masks months ago. I do still see the occasional mask-wearer though.

Although neither Mrs Bob nor I wear masks, we do keep our distance from other people. Neither of us works, so that’s a problem we don’t have to face, but we do go to restaurants, shops and other places where people congregate.

I was in the pharmacy a few days ago and, unusually, there was a queue. It was noticeable that even without signs exhorting us to “Keep Two Metres Apart” everybody was doing just that.