Americans are very stingy with prepositions:
American: I wrote them British: I wrote to them
American: I wrote them British: I wrote to them
Edit: Interestingly(?), the government official leaflet adds an "at": https://www.gov.uk/government/publications/coronavirus-covid...
I've never heard that construct. Are you by chance referring to Morton Salt's motto "When it rains, it pours"?
I think it was HN that lead me to the discovered not too long ago that the phrase originated from an early-20th-Century ad campaign of theirs following the introduction of magnesium carbonate, an anti-clumping agent: https://en.wikipedia.org/wiki/Morton_Salt
In the US - in the Arkansas Ozarks, specifically - I've heard the other version in the same context.