Snowdonia Attractions


John Lloyd of Inigo Jones Slate Works gives tells us about the long history of North Wales’s iconic stone.

How many companies have been in operation on the same site for over 150 years? At Inigo Jones we have been here at Tudor Slate Works since way back in 1861. The company was originally set up to produce school writing slates and made thousands of them over a period of 50 years, with many being exported all over the world. Some of our older visitors still fondly remember writing and doing sums on the school writing slates, which they are now only seen around the country in Museums depicting Victorian times.

But the story of Welsh slate goes back even further. Between 550 and 400 million years ago the area we now know as North Wales was covered by a very deep sea, at the bottom of which mud accumulated. This mud, due to water pressure, formed a very fine mudstone. Around 400 million years ago Wales and Scotland (still covered by sea) collided with the North American continent. The collision at a depth of about 6km, created high pressures and temperature of up to 250 degrees. Under such conditions the mudstone was transformed into hard slate. Interestingly enough this is the reason why slate from Newfoundland has the exactly same characteristics as the famous Penrhyn Blue Welsh slate from North Wales.

Why did the company set up here? Simple: there was a water wheel on site to drive the machinery to cut the slate. The water wheel operated until 1952 when it was dismantled, rumour has it because the new double decker buses could not fit under the water chute that fed the wheel. The wheel was replaced by an oil engine known locally as ‘Injan Grafog’ which provided the power for the works until we switched to electricity in 1960. It wasn’t the end of ‘Injan Grafog’, which was exported to Baghdad to pump water.   The company also had its own railway siding to deliver and collect slate, operated by the London and North Western Railway company. Any collections or deliveries of slate had to be loaded or unloaded within 10 minutes or the railway company would raise a delivery surcharge. The railway line was closed as part of the Beeching cuts in the 1960s and lay dormant until part of it was repurposed for lorries carrying material from Bryncir for the construction of the Dinorwig Power Station in Llanberis.