Sea-heath at Three Cliffs Bay

Yesterday I went to see if I could find the small 9 inch patch of Sea-heath (Frankenia laevis) reported by P.G. Garner in 2002. I was amazed to discover the plant has proliferated since then and is now abundant along the shoreline at the back end of the bay. I counted some 122 plants, including some amalgamated into mats >2m across, though most were less than <30cm. This is a recent colonist in Gower, though another healthy population was also discovered by Charles and Hilary Hipkin in similar habitat at Crymlyn Burrows. How it's arrived at these isolated sites is a mystery to me?

A carpet of Sea-heath along the strandline with Pennard Castle behind. The woodland on the left has some good specimens of Small-leaved Lime, with its upward-turned flowers.