That says that there is less pub-going recently. And I do see some articles saying that many pubs aren’t using up their allotted time because traffic has fallen off. So that may be an effect in addition to this.

This one, though, describes the legal mandates as a much-longer-running phenomenon, legislation dating all the way back to World War I:

https://londonlhr.online/why-do-london-pubs-close-early/

The World War I Defense of the Realm Act (DORA) of 1916 is where the practice of early shutting originated.

The goal of the ordinance was to prevent excessive drinking and maintain sobriety among those employed in weapons plants and other wartime industries.

Despite DORA’s long-standing repeal, its effects on pub closing times have persisted.

https://en.wikipedia.org/wiki/Defence_of_the_Realm_Act_1914

Alcoholic drinks were watered down and pub opening times were restricted to 12 noon–3pm and 6:30pm–9:30pm. (The requirement for an afternoon gap in permitted hours lasted in England until the Licensing Act 1988.)

An article from 1987 talking about the Licensing Act 1988:

https://www.latimes.com/archives/la-xpm-1987-06-25-mn-10623-story.html

The current law that affects about 50,000 pubs dates back to 1915. In that year, the Defense of the Realm Act was introduced to restrict the nation’s 18-hour drinking day so that production of munitions would not be impaired. The government promised that normal service would be resumed at the end of the war, but the promise was never kept.

Hurd said that under the new bill, public houses will be allowed to stay open from 11 a.m. to 11 p.m. six days a week. He did not specify what the Sunday hours will be.

Licensing laws have already been liberalized in Scotland. But elsewhere in Britain, pubs can open only nine hours a day (9 1/2 hours in London) Monday through Saturday and only five hours on Sunday. Basically, pubs can open only at lunchtime and in the evening until 11 p.m.