Sorry to disappoint you, Hugo and Nemesis but I'm not a particular expert! I agree with Nemesis that the plant in Hugo's photo does look like common scurvy grass but I think that we have Forum member who could give us a definite identification. The interesting article to which Orme Vixen posted a link mentions Wendy McCarthy, who is an expert and who, unless I'm much mistaken, has joined the Forum. So, if you read this, Wendy, we'd love to hear from you!
Going back to an earlier question from Trojan of whether anyone has seen the wild cotoneaster, Cotoneaster cambricus, you should be able to see a "tame" one in the wildflower garden at the Great Orme summit visitor centre.