I went on a tour round a few years ago and it was notable for using Gas Insulated Transformers, which are unusual outside of Japan if I remember rightly. There were amazingly strict planning regs that required the installation to be super quiet, so the building had a surprising amount of sound insulation.
There's a fake "house" at the end of my street. It's actually a telephone exchange: https://www.google.co.uk/maps/@55.9050155,-3.2075701,3a,75y,...
There's normally an Openreach van or two parked outside, which gives the game away, but driving past you wouldn't notice.
My favourite is Dewer Place sub-station, despite the fancy frontage it was purpose built in 1894 as a sub-station: https://www.google.co.uk/maps/@55.9465325,-3.2112386,3a,75y,...
I went on a tour round a few years ago and it was notable for using Gas Insulated Transformers, which are unusual outside of Japan if I remember rightly. There were amazingly strict planning regs that required the installation to be super quiet, so the building had a surprising amount of sound insulation.