As illustrator Ben Langworthy draws his way around the lighthouses of the UK coastline — finally! He finds one with a loo.

Trwyn Du, also known as the Menai Lighthouse, was first lit in 1838 and stands around 96 feet high. With its vertical walls and castellated ramparts it looks as if it would perhaps be more at home on a medieval fort than on a rock of the Welsh coast.

This unusual lighthouse was the first to be designed by the engineer James Walker. Eager to pioneer new innovations, Walker also installed an early water closet with a drain at the base of the tower. This proved a bad idea however, as during heavy weather seawater had a tendency surge up the drain, giving a nasty shock to any unsuspecting keeper trying to use the facilities at the time.

The lighthouse also overlooks the remarkable Puffin Island – so named for the thousands of the rare seabirds that make their home there.