Back in February the WHO's position was that it wasn't yet a pandemic and that masks were useless. Their advice was merely to protect healthcare workers and to protect those who were most vulnerable.

Expecting Boris to have mandated mask usage in February is bizarre, not a single country or health authority anywhere was even considering doing that back then and remember - all the scientific studies said that masks were of unclear or no value in stopping the spread of flu, one of the closest analogues. So that's some pretty serious Captain Hindsight behaviour going on here.