It looks like they do all have a lot of plugs. https://www.news.com.au/lifestyle/home/interiors/a-house-for-sale-for-25m-is-covered-in-power-points-and-no-one-knows-why/news-story/628d6cc69c74ab98224b03f101ba2c97

Not sure England's code would even allow it, but maybe there are multiple circuits tied to a few plugs each, and each room shares the circuits in the same config. This I know would be a huge pain to wire, especially when it seems some may be added after the plaster.