The historic heart of Hydro lies in the underground passages and water-works hidden away from prying eyes.  I visited Loch Lednock in the South of the Breadalbane system and by luck the main dam vent was purging water and pressure ahead of essential maintenance.

Standing at the centre of the dam peering over the edge gives one the sense of the “gravity” and energy the dam stores before being converted to electricity. With a massive difference in height between the loch level and ground level below the huge stream of water is over 50ft high squeezing between a gap in the valve of only 2 inches.

When directed down underground tunnels this water pressure would end by spinning the turbines of St. Fillans power station. The station itself is more James Bond than utility company. After driving down a steep access road another spotless plant room but underground with bedrock lined walls awaits.

So Dr. Evil how do the civil engineers access the pressurized tunnels..  Through the atmospheric, slimy, eerily lit spoil pipe of course..