On 25 October 1859, the same Atlantic gale that built the modern pebble bank at Abermawr destroyed the ship Charles Holmes off this coast. All 29 people on board drowned. Their bodies washed up on the shingle here and at neighbouring Aberbach, and Captain C. H. N. Bowlby was buried in the churchyard at Granston. The storm that took them rearranged the bay itself, piling the great wall of round stones that walkers now crunch across on the Pembrokeshire Coast Path. The marsh and woodland behind the beach soften the scene into something pastoral, but Abermawr is a coast that has form for swallowing ships, and the prehistoric tree stumps visible at low tide are reminders that the sea has been chewing this land for a long time.

Isambard Kingdom Brunel changed his mind about Abermawr twice. First, in the 1840s, he surveyed it as the western terminus of the South Wales Railway, the place where London-bound trains would meet Atlantic ships. He rerouted the line to Neyland instead. Then, in 1866, Abermawr got its Brunel moment after all. His steamship Great Eastern laid a telegraph cable across the Atlantic from Trinity Bay in Newfoundland to Valentia Island in Ireland. The wire crossed Ireland overland, plunged back beneath the Irish Sea at Wexford, and surfaced here. For the first time in human history, a message from North America could reach London in minutes rather than weeks. Operators in the iron hut relayed every word.

A second cable came ashore at Blackwater in 1880, and Abermawr settled into a quieter rhythm as a relay station. During the First World War a small detachment of soldiers guarded the site, alert to a Britain whose conversations with America now ran along these few thin threads of copper. Then another storm did to the cables what the 1859 gale had done to Charles Holmes. The connections snapped sometime in 1922 or 1923, and the company decided not to rebuild. The operators packed up. The hut closed. Abermawr, which had briefly been one of the most important places in the British empire, slid back into being a beach.

Today Abermawr is a Site of Special Scientific Interest, protected for the wildlife that thrives where shingle meets marsh meets ancient oakwood. Walkers on the coast path drop down off the headlands and step out into the bay between Porthgain and Abercastle, the air thick with salt and gorse. The currents offshore are dangerous, but the low headlands keep the wind manageable, and on a clear day you can stand on the pebbles and look west toward the open Atlantic that once carried Brunel's wire, and Brunel's ships, and a great deal more besides. The cable hut, white-walled and converted, watches it all from above the high-water mark.