While still in High School, in 1972, my father's business associate, a Liverpudlian, explained this song to me line by line. I can't remember the significance of a few of the innuendos, e.g., the barber "showing photographs of every head he's had the pleasure to know," but most of it is pretty clear in my mind.
The banker was a flasher - he never wore a mac (raincoat) in the pouring rain, because he wore it when it wasn't raining. The little children laughed at him behind his back because they knew.
I can't remember the significance of fireman's hourglass - maybe a pocket watch, but there is a portrait of the Queen in every Brit's pocket (coins & bills). He plays "pocket pool" - fondling himself and keeping his fire engine clean. He uses the digging for coins excuse to cover for his proclivities.
A four of fish and finger pies - in summer - refers to "fingering" the girls when they wore short skirts (who, obviously, are somewhat fishy spelling). Blame Sir Paul, not me, for the innuendo.
The pretty nurse selling poppies from a tray was selling heroin. Plus, it referred to a local holiday, and brings in a little LSD insight (feels as if she's in a play).
All and all, a great bit of R & R trivia!