My industrial training for a year, in 1973, included working for this ancient civil engineer in Surbiton for 3 weeks. My interview was conducted sitting in an armchair in front of a glowing fireplace with a dog snuggled in front of it, drifting off in the doggieland. He showed me a sketch on his drawing board in his front room, representing a tunnel in the Welsh mountains, in other words it was rock (!) and relatively featureless. No doubt exciting when you have to do some rock blasting. All this to enable rapid release of stored water to feed the turbines (needed for electrical capacity during peak times and all that). The early green hydroelectric energy, blah ...