Why are fewer English people going to their local pubs for a drink? Are they aware that many pubs are shutting down due to lack of customers?

You have to understand what the attraction of the English pub was in the first place.

You have 1001 sources of entertainment on TV and the Internet

A range of alcoholic drinks

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Your home has more comfortable seating and a garden

The pubs with the best chance of survival long-term recognize that they can’t just get away with the same 3 beers, ropey wine and pub-grub. Why pay more for something worse than you can get at home for less?

Entertainment (pre TV and radio)

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But now:

You can get takeaway or even cook yourself a wider range of food of good quality

You can get a wider range of quality drinks at lower prices from a supermarket

What is a real life example of the Streisand Effect?

Back in the day (early 20th century and before) the English pub offered things you couldn’t get in a working-class home:

Comfortable seating in a warm, cozy environment, or a nice pub garden

In the mid to late 20th century they added food, without the inconvenience of cooking it or washing up.

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They need to offer either food of a quality you can’t get at home (true gastro-pub experience) or alternative entertainments - live music, poker nights, sports viewing etc.