Little-known little gem

AS tunnels go, it's not the longest: Coed Helen curves gently for a mere 75ft, making it quite possibly the shortest ever built in Britain.

- Andrew Forgrave

The long abandoned Coed Helen Tunnel on the old Nantlle Tramway near Caernarfon

(PICTURE: DISUSED RAILWAY TUNNELS UK)

It has another unusual claim to fame too, being part of the Britain's last railway line on which freight was hauled by horses.Today, the tunnel near Caernarfon is sealed up and largely forgotten, its hefty stonework still in great condition after almost 200 years.

One of two tunnels on the Nantlle Tramway, this one was built to go under a public road before hugging the banks of the Afon Seiont.

The line's other tunnel also navigated under a road - one that was altogether more private.

To appease the sensibilities of the local aristocracy, the 150ft tunnel carried the tramway beneath the driveway of Plas Dinas house, Bontnewydd.

Now Grade II-listed, this was the ancestral home of the Armstrong-Jones family - and onetime home to Princess Margaret.

Coed Helen tunnel is now gated at one end and blocked up at the other, scarcely visible through a tangle of vegetation.

If they know what to look out for, Welsh Highland Railway passengers can catch a glimpse as they steam past.

Walkers occasionally divert to take a closer look. Visitors have included Vince from Disused Railway Tunnels UK, who was quite taken by the diminutive tunnel.