I can't remember if the city department stores had a midweek early closing day as well, I don't recall it so maybe this was their way of a 5.5 day working week. Taunton was unusual in having early closing on Thursday, and different "Thursday afternoon" events were quite common. The 2pm train to Minehead was notably busier on fine summer Thursdays. Market day, normally midweek elsewhere, was Saturday, busiest of the week. That's gone as well; the significant livestock market, close to but not at the station, was built I understand in the 1920s to replace the open area in the town centre. Our gardener at the house was a farm labourer from a friend's farm, who (outside harvest month) worked five long days, but on Saturday got the bus a few miles into town, started on the garden at 8.30, finished by 12.30, my father paid him, then he went into the town, met up with his mates in a pub, and consumed much of his gardening earnings!
It always was said that the town council, where established shop owners were over-represented as councillors, made fully sure that nobody traded on a Thursday afternoon, or outside established shop hours. There was actually a by-law which enforced this.