OK, here's a little puzzle for you; also a short science lesson!
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When I was a kid, my Grandfather used to work for the local electricity board at the place in the picture. Later, When he became unwell, his bosses gave him the job of travelling round the sub-stations, looking after the gardens. I sometimes went with him. The inside of those sub-stations scared the s**t out of me. Here's a pic. of one in Noctorum, at the junction of Noctorum Rd. & West Rd.
Now for the science: in those days (1940's) the power supply to the houses was DC. You can only transmit DC just over a mile before losses in the cable make it useless, so power was generated in AC & sent at high voltage (so few losses) to the many sub-stations, where it was reduced in voltage with transformers & then fed into mercury vapour rectifiers to change it into DC to be supplied to houses. It was those rectifiers which scared me; about 4 Ft. tall, a huge glass bulb with mercury in & glowing a terrible purple with the mercury vapour & emitting a loud humming. There's still some of these sub-stations around. You can see the remains of one at the top of Singleton Ave. & the one in Noctorum looks the same as it ever did.
It was because our power supply was DC that I could never have a Hornby Dublo electric train set. I guess the power supply was about 200 Volts & you couldn't use a transformer to reduce it.
BTW, in those days, there was nothing like MANWEB; the National Grid was in its infancy & each town generated its own electricity supply. The power station pictured was owned by Birkenhead Council, which is why it has the town crest over it.
Does anyone know where it is?