Ffestiniog Railway: Slate, Narrow Gauge and the Mountain Route to Porthmadog

High in the mountains of north-west Wales, the town of Blaenau Ffestiniog sits among grey hillsides that are not hillsides at all, but tips of waste slate piled over two centuries of quarrying and mining. From here a railway less than two feet wide winds 13.5 miles down through oak woods and along mountain ledges to the harbour at Porthmadog. The Ffestiniog Railway was built in the 1830s to do one job, carry slate to the sea, and the way it was designed to do that job explains almost everything you see from the carriage window. On the fifth day of our Canals and Railways in the Industrial Revolution tour, the group rides the line from Blaenau Ffestiniog down to Porthmadog, the same direction the loaded slate trains once ran.

Slate and the industrial landscape of Blaenau Ffestiniog

Slate was the great building material of Victorian Britain. It splits into thin, even sheets, it is light for its strength, and it keeps out the rain for generations, so as towns grew through the nineteenth century the demand for roofing slate grew with them. North-west Wales held some of the best deposits in the world, and the mountains around Blaenau Ffestiniog became one of the industry’s centres. Where the great quarries of Penrhyn and Dinorwig further north worked their slate in open galleries cut into the mountainside, much of the Ffestiniog slate was worked underground, in great chambers mined deep inside the mountains.

The town grew up around the workings. Rows of terraced houses, chapels and quarry buildings were built of the same grey stone that was being extracted, and the waste rock, which in slate working far outweighs the usable product, was tipped down the slopes in great terraces. The tour itinerary describes Blaenau Ffestiniog as the industrial centre for the largest slate mine in the world, and the underground workings can still be visited at Llechwedd Slate Caverns. In 2021 UNESCO inscribed the Slate Landscape of Northwest Wales as a World Heritage Site. One of its six components is named for this place and this line: Ffestiniog, its slate mines and quarries, the “city of slates”, and the railway to Porthmadog.

The problem was distance. The mines were high in the mountains, and the markets for their slate were reached by sea. Slate is heavy and brittle, so every time a load is handled it costs money and some of it breaks. A railway running the whole way from the mines to a harbour would carry it from quarry to quayside in a single movement.

Why was the Ffestiniog Railway built to such a narrow gauge?

Because the mountains left no room for anything wider. The line was laid to a gauge of 1 ft 11½ in (597 mm), less than half the 4 ft 8½ in standard gauge used on main lines. A narrow track can turn on much tighter curves, and tighter curves meant the route could cling to the contours of the valley side, wrapping around spurs and into side valleys on ledges and short embankments rather than demanding the deep cuttings, long viaducts and tunnels a wider railway would have needed. The small, light wagons also suited the slate trade, and they could run on the tramways inside the quarries themselves.

The company was created by Act of Parliament on 23 May 1832, and it still describes itself as the oldest surviving railway company in the world. It was promoted by Henry Archer, who raised much of the capital in Dublin, together with Samuel Holland, a quarry owner, and the survey and construction were carried out by James Spooner. Built between 1833 and 1836, the line opened on 20 April 1836.

Gravity, horses and the dandy wagon

Spooner’s real achievement was the gradient. Blaenau Ffestiniog stands at about 710 feet (216 metres) above sea level, and the line was laid so that it fell steadily towards the coast, at about 1 in 80 for much of its length. That was steep enough for loaded wagons to roll all the way down by gravity, yet gentle enough for brakesmen to keep them under control. Two brakesmen rode each descending train, and long trains of more than 80 wagons needed three.

Getting the empty wagons back up the mountain was the job of horses. Each horse hauled empties uphill, and for the journey down it rode in a small wagon of its own, called a dandy, attached to the descending train. The system was cheap and effective, and by 1856 the timetable allowed for up to 70,000 tons of dressed slate a year. It was also close to its limit. As demand rose, the company needed a way to move more wagons uphill faster than horses could pull them.

From quarry to Porthmadog

The railway’s lower end depended on an earlier piece of engineering. Between 1808 and 1811, William Madocks built a great embankment, known as the Cob, across the estuary of the Afon Glaslyn to reclaim farmland behind it. Diverting the river scoured out a natural deep-water harbour beside the embankment, and Parliament approved a harbour there in 1821. The town that grew around it took his name: Porthmadog, once spelled Portmadoc. The railway was carried along the top of the Cob to the quays, so slate could go straight from wagon to ship.

The result was a busy port. By 1873, more than 116,000 tons of slate were being exported through Porthmadog in over a thousand ships, and the town built its own fleet of fast wooden schooners, the last of which was launched in 1913. The harbour’s trade then faded as main-line railways arrived: the London and North Western Railway reached Blaenau Ffestiniog in 1879 and the Great Western in 1883, offering a direct route to the cities of England. By 1925 less than five per cent of Ffestiniog’s slate output left by sea.

Steam, passengers and the double Fairlie

Steam arrived in 1863, when the company accepted a tender from the London locomotive builder George England and Co. The first engine, Mountaineer, was delivered on 18 July 1863, followed by The Princess, and the first official steam train ran on 23 October that year. The Board of Trade allowed passenger trains in 1864, making the Ffestiniog the first narrow-gauge railway in Britain to carry passengers, and cheap services for quarry workers followed in 1866.

Steam brought a new problem: the small engines struggled with the growing slate traffic. The answer was the double Fairlie, an articulated design with two boilers joined back to back, a central cab and a swivelling power bogie at each end, giving far more pulling power while still taking the line’s tight curves. The first ran on the Ffestiniog in 1869, and Little Wonder was demonstrated in 1870. In 1879 the railway’s own works at Boston Lodge, at the far end of the Cob, built Merddin Emrys to a design by George Percival Spooner. It has spent its entire working life on the line.

Boston Lodge itself is older than the railway. The site first held barracks, stables and smithies for the men and horses building the Cob, and they were brought back into use when the line opened in 1836. It remains the railway’s engineering works today.

The mountain railway experience

Riding down from Blaenau Ffestiniog is the best way to understand Spooner’s line, because you travel with the gradient the slate trains used. The train leaves the town among the slate tips and quarry buildings, passes Tanygrisiau and the reservoir of Llyn Ystradau beneath the Moelwyn mountains, and then makes its way through a tunnel and around the loop at Dduallt before dropping into the oak woods of the Vale of Ffestiniog. Tan-y-Bwlch station, at around 443 feet, is less than eight miles from Porthmadog. Below it, the line runs on ledges high above the valley floor, with views across the Dwyryd estuary, before it reaches Boston Lodge and makes the final run along the Cob into Porthmadog.

The train is part of a long day on the tour. The group crosses Wales through Snowdonia to Anglesey to see Telford’s Menai Bridge, rides from Blaenau Ffestiniog to Porthmadog, and stops to view Snowdon, at 1,085 metres the highest mountain in Wales, before returning to Llangollen for the night.

How long is the train journey from Blaenau Ffestiniog to Porthmadog?

Allow around an hour and a quarter for the 13.5-mile run. Steam trains on a narrow mountain line are not fast, and that is much of the point: the pace lets you take in the changing scenery, from slate tips to woodland to estuary. Even in 1900, when the railway was a working freight and passenger line, the timetable allowed an hour for the journey.

How much walking does the railway day involve?

The ride itself is seated, so the walking comes at the stations and the stops either side. The tour as a whole is rated Level 2 (Moderate): most days involve three to five hours of activity, the equivalent of walking up to 8 kilometres, sometimes on uneven ground, and travellers need to manage stairs and carry their own luggage. The Snowdonia day is a long one, so it is worth bringing a layer for the carriage and comfortable shoes for station platforms and viewpoints.

Preservation and the industrial afterlife of the route

The railway’s working life ended in two stages. Ordinary passenger services stopped on 15 September 1939, and slate traffic ended on 1 August 1946. The company was never formally wound up, because its Act made no provision for abandonment, and that legal survival made revival possible. In 1954 Alan Pegler, with £3,000 lent by his father, took control of the company and became its chairman, and volunteers began restoring the overgrown works at Boston Lodge that September.

Trains returned in stages: across the Cob to Boston Lodge in 1955, to Minffordd in 1956, Penrhyn in 1957, Tan-y-Bwlch in 1958 and Dduallt in 1968. Beyond Dduallt, the old route had gone. In the 1950s the Central Electricity Generating Board built the Ffestiniog pumped storage power station, and its lower reservoir, Llyn Ystradau, flooded about a mile of line north of the original Moelwyn Tunnel.

The answer was the Deviation, a new route about 2.5 miles long built between 1965 and 1978, largely by volunteers. To gain height quickly enough to pass above the reservoir, the line climbs in a spiral at Dduallt, crossing over itself and gaining 35 feet in the loop. It is the only spiral on a public railway in the United Kingdom. A new Moelwyn Tunnel, 310 yards (280 metres) long, was driven between 1975 and 1977 by three Cornish tin miners. The Deviation opened to Tanygrisiau on 24 June 1978, and trains finally returned to Blaenau Ffestiniog on 25 May 1982.

Is the Ffestiniog Railway the same as the Welsh Highland Railway?

No, but they are run together. The Festiniog Railway Company also owns the Welsh Highland Railway, which shares the same narrow gauge and was fully reopened in 2011. The two lines meet at Porthmadog, so occasional trains can run right through to Caernarfon, about 40 miles in all. On the tour, the ride is on the Ffestiniog line, from Blaenau Ffestiniog to Porthmadog.

A railway that explains its landscape

The Ffestiniog Railway makes a useful contrast with the other transport routes on the tour. The next day stays close to Llangollen to explore the Llangollen Canal and the Horseshoe Falls weir that feeds it, and to cross Telford’s Pontcysyllte Aqueduct by boat, where the waterway engineers met the mountains with masonry and iron rather than with tight curves. Later, in north-east England, the Stockton and Darlington Railway shows the other path railways took, on standard gauge and built for heavy coal traffic.

Taken together, these routes show how the shape of the land and the nature of the cargo shaped every decision the engineers made. Our overview of Britain’s canals, railways and industrial heritage places the Ffestiniog alongside the other stops on the journey, and the Canals and Railways in the Industrial Revolution tour lets you ride the slate line from the mountains to the sea in a small group of 6 to 14 travellers, departing in April and September 2027.