Re: The UK mostly powered by coal?
"I was always irritated by Didcot power station, ridiculous on the Berkshire downs. "
I'd hardly call Didcot in Oxordshire, and at the very eastern end of the Vale of Aylesbury as being on the Berkshire Downs! Admittedly its not far, but certainly not on them.
I would suspect that the location of the power station goes back to the layout of the national grid of the time. Most power stations were built near the deep coal pits that produced their fuel in the 1960s, hence the East Midlands, Yorkshire and South Wales power stations. In the case of Didcot all the coal had to be pulled from South Wales, which was a considerable cost, and I guess that the transmission links between London and Wales had insufficient capacity at that time. The CEGB would have done a detailed NPV assessment between the alternative of building a new station in South Wales and duplicating the transmission links to take the power to London, and then selected an approximate location that happened to be around Didcot, probably because that was already a key switching station on the grid as was. Building even nearer London would have raised the property costs and mixed the coal trains with commuter rail traffic, and I guess that's why it was no nearer to London.