I have my summer house at a similar facility
My summer house in Eastern Europe is at a similar facility built at about the same time. Bigger too. In fact big enough to be one of the primary elements in balancing the grid so you do not burn expensive gas to compensate for spikes.
There is a different way of looking at the Electric Mountain - it is a sad testament of what we could achieve if it was not for the misconceived NIMBY and "historical preservation" attitude. Historically, the Lake District in its current form was created in the 18th and 19th century to provide the industry in the North of England with energy and water for all the metal works. It is not a natural feature (at least most of it).
It could and should have been converted into one giant hydro-accumulation facility - a giant Electric Mountain. If it did, the UK would have balanced the grid without resorting to any gas burning. This would have fit its original purpose too. However, anyone daring to harbor such thoughts is likely to see a lynch mob carrying National Trust membership cards within 15 minutes after speaking it out in public.