It looks like Jewels of Opar (Talinum paniculatum). It has cute little pink flowers, but boy, can it be a pest! Anything that will kill Purslane will kill it, but be sure to protect surrounding plants. I use something containing trimec, along with a surfactant to keep it on the leaves. Good luck!

I doubt if Talinum paniculatum is to be found growing in Swansea.
Still whatever it is all you can do is to paint the leaves with Roundup. You can buy a thicker version of it, but mixed with a non fungicidal wall paper paste it will stick to the leaves. You will have to repeat the process a fair number of times to be successful. Oh and buy the undiluted Round up not the ready ixed, if you are going to add it to anything to make it stick to the leaves.

If you have some sort of a blow torch. The cookery ones are readily available. maybe that would work after grubbing out the leaves. A good going over the crevice with heat might do the trick. Just a thought that this is worth a try. Years ago we had a long tube that made a fearsome roar to burn off weeds from pavings.

It's not Centranthus, is it? Does it have pink or white flowers a bit later on?

I'd agree with Owdboggie. It will take time to get rid of it.

don,t know which these have as I hav'nt seen the flowers on these yet, but we did have one or two in the last property and they had losely packed pink or white pom pom like flowers ( I have also seen them in red) In the last property they were making the garden wall fall down as their roots grow right down into the brickwork. so I hope I can get rid of them before they do the same here.

I'd agree with you if it is Centranthus. You do need to take action!

Good luck.

and you know i have never been able to grow it. despite several attempts.

It grows like weeds down here, Sbg, and usually in people's walls. I like it, but I daren't have it anywhere near our stone walls, as it seeds itself into cracks - then watch the wall fall apart!!

yes I've noticed it in the strangest of places.

Pretty, though.............

I'm curious, why wouldn't Jewels of Opar be found in Swansea? Although it is a native of the American Southwest, it comes from higher elevations, is quite frost hardy, and isn't particularly dependant on heat. Just for my own education, if you all are willing!

I don't know what it is, Tugbrethil. Do you know what the latin name is, please?

Talinum paniculatum

http://www.robsplants.com/images/portrait/TalinumPaniculatum040723.jpg

and

http://pgjennielove.files.wordpress.com/2008/09/talinumpaniculatum0407151.jpg

a.k.a. Fameflower