Thats navelwort, Umbilicus rupestris.

Also called Wall Pennywort :)

Ah Hywel, that must be from the shape of the leaves!

So is 'navelwort' I believe :) it looks more like a navel than a penny lol

Thanks all !

True Hywel - whoever saw a frilly penny? I just went outside to see the ones on our bank were frilly but although there were two flower spikes there were no leaves at all!

That's strange.