Penclawdd (Welsh: Pen-clawdd) is a village in the north of the Gower Peninsula in the county of Swansea, Wales. Historically, it was part of Glamorgan. Penclawdd is most famous for its local cockle industry which goes back for many years to Roman times. It falls within the Penclawdd electoral ward. It is one of the larger villages on the Gower Peninsula. Part of the village is perched on a high location, enjoying panoramic views over the Loughor estuary and surrounding Gower countryside, while the main part of the village stretches along the edge of the estuary. Being so close to an estuary, Penclawdd is thriving with wildlife. It is plentiful in birdlife and with horses that roam the estuary. The built-up area had a population of 1,935.

Up until the end of the 19th century Penclawdd was a thriving sea port. The Penclawdd Canal connected to the Burry River at Aberkeddy. The village was renowned for coal mining and its extensive tinplate, copper and brass works, operated by the Cheadle Copper Company. There was a time when Penclawdd had a forge, twenty grocers, three butchers, three drapers, four fish and chip shops, eleven pubs, a cinema, the still remaining three chapels and a church and a busy railway station. The original railway platform still remains today. Also, built in 1807, a now derelict Hermon Chapel was used to help ships navigate the estuary.

Around 1800, John Vivian of Truro, Cornwall, became managing partner in the copper works at Penclawdd and Loughor then owned by the Cheadle Brasswire Company of Staffordshire. The Vivian family eventually ran large copper mining, copper smelting and trading businesses in and around Swansea (Vivian & Sons) and, throughout the 19th century, did much to develop Swansea into a city.

At about 5p.m. on Wednesday, 28 October 1942, a Bristol Blenheim bomber crossed the Burry estuary at a height of 5,000 feet. Over the north Gower salt marshes, the plane dropped a single bomb. The local residents didn't know it, but they’d just become part of the army's biowarfare experiments.

The bombing run wasn't out of the ordinary. An artillery range had been set up in the area at the outset of the war and a number of weapons were tested there, including mustard gas.

The target for this bomb was once again sheep. Three pounds of liquid anthrax spores detonated on the sandy ground of the Burry Inlet, upwind of two tethered lines of sixty animals.

Two of the sheep died of anthrax poisoning. Others fell sick but recovered. All the surviving sheep were slaughtered after seven days and their bodies buried at the edge of the estuary marshland. The scientists believed that the incoming and outgoing tide had disinfected the land and no warnings were required. The remainder of the army's anthrax experiments moved back to Gruinard. The people of Penclawdd were left none the wiser what had happened in their own backyard.

It wasn't until 1982 that Keith H. Hopkins, secretary of the local Labour Party, went to the media to address local rumours about the bombing. Hopkins had three demands.