As ever, the UK is a late arrival to the party. Other countries have had this requirement for some time. This is about risk reduction so this requirement isn't going to stop people who are infectious entering the UK because we know there are issues with false negatives (particularly later flow assays which are practically useless) but it will have some impact on transmission simply by dissuading people from making casual, short trips into and out of the UK because of the additional burden.

I imagine the requirement will be eased once hospitalisation rates drop and priority groups in the UK are vaccinated, and frankly, once the temperature rises as this will help to reduce mortality rates to some degree. I consulted my crystal ball and my speculative view is this will be at some point in early May, but I might be completely wrong about that.