Well, when I upgraded my flat’s electrical installation it was a mix of all kind possible wiring fashions from the last century at semi-random order, united by the fundamental principle of all British builders: “good enough”. And yes, I had branches on aluminium cables, including at the incoming mains. And all of that was crowned by a fuse box so ancient that it raised eyebrows of the electrician who mumbled something about 1942 being the last year legal per current regulation. Which in turn raised my eyebrows. All that rubbish was scrapped and replaced with the latest RCD fusebox, properly certified and even equipped with a smart meter (that the supplier previously refused to install due to incompatible wiring). But as far as I understood from talking to people, such an approach isn’t very popular and “good enough” continues to be the fundamental principle in British housing industry.