From the Menai Strait to Dolgarrog

For the fourth programme Mike sets off from Traeth Lafan near Penrhyn Castle and follows the fortune of the Pennant family who made their fortune in the slate industry.

Into Bethesda, the slate quarrying town, which prompted George Borrow to write, 'If Bethesda's name is scriptural, the manners of its people are by no means so' and onwards and upwards along the stunning Nant Ffrancon Valley along an ancient Roman Road.

At Cwm Idwal, which Mike describes as, 'a gothic cathedral of nature' there is a flurry of human activity as this is the starting point for many a walker and climber.

Mike pitches up in a tiny campsite in the lee of Tryfan mountain before hitting the 'colossus of roads' the following morning. This is the A5, Thomas Telford's amazing feat of engineering that runs from London to Holyhead.

Down the Ogwen Valley and into Capel Curig, then it's off the trunk road at the Ugly House and a winding ramble through the Gwydir Forest past Geirionydd Lake to the woollen mill of Trefriw. Here in this old spa town Mike drinks the iron flavoured water of the chalybeate spring before supping something more palatable at the Fairy Falls, a pub run by harpist Dylan Cernyw.

Mike's final destination is the forlorn Cwm Eigiau high above Dolgarrog. The valley harbours a dark secret.

Mike describes the tragic events that took place in 1925. 'On a wet Monday night in November 1925, a crack appeared in the new dam that had been built to encase a reservoir at Llyn Eigiau. When it was being built fifteen years earlier, the contractor had pulled out, claiming that the work was sub-standard and corners were being cut.

'And so it proved. The crack gave way to a huge breach, and millions of tons of water poured out, cascading down the valley and overwhelming a further reservoir below. The contents of the two reservoirs then raced down and smacked headlong into the village of Dolgarrog, twelve hundred feet below. Sixteen people were killed instantly as an entire section of the village was washed away.'