Although this song dates from a time slightly before mine I'll try to help with some of the references.

Hull Fair waltzers, bopping to Brenda Lee.
Hull Fair is an annual fun fair, the biggest travelling fair in Europe, and Waltzers are one of the rides. Bopping is a form of dance, a gentler form of jiving, and Brenda Lee's hits were often played on the waltzers' PA. People could use this as an impromptu dance hall.

River boat jazz cruise...
The Humber Ferries (in the days before we had a bridge) used to do Sunday or evening cruises with a band on board. I imagine that the two-nineteen was a jazz band, but I'm not sure.

I imagine that Lal had someone in mind from her youth when she wrote this song.