Lyrics written before flue gas desulfurization when there used to be more pretty blue smoke from coal plants.

“Sitting in an English garden
Waiting for the sun
If the sun don’t come you get a tan
From standing in the English rain”

To be fair to the Beatles, Great Britain adopted FGD as early as the mid 1930s on a few power plants due to high sulfur content of British coal but it wasn’t widespread until decades later. But they still have a lot of problems with acid rain in Great Britain.