The rocks on Dinas’s beaches provide an anchorage for an interesting collection of molluscs and lichens, many of which are indicators that the air is clean and general pollution levels are low. Our local Cwm yr Eglwys is included on the Marine Conservation Society’s list of best beaches 2015.

This rock on Aberbach, however, is a rare reminder of how things used to be. Our childhood outings to the beach would invariably involve getting tar on our feet. The stickiness could be removed, along with the top layer of skin, by rubbing with sand but it would invariably leave brown (apparently indelible) streaks. If the tar got onto towels or bathing costumes it would be there until the end of the holidays. Then we’d apply trichloroethane or ‘Dabitoff’ – an ozone depleting carcinogenic chemical with a heady smell that even back in those days we’d know not to put on our skin.

As early as the mid 1930s most of Britain’s beaches were affected by oil pollution that came ashore from the major tanker routes in UK waters.  Following the introduction of international regulations in the 1970s, preventing ships from washing out their tanks at sea, our part of Pembrokeshire, at least, is clean again.