Ranunculus repens - Creeping Buttercup. Method of removal, as for any unwanted plants, is to pull or dig them out. Notice it is growing in an area where the grass is sparse. Weeds such as this take advantage of clear soil so, improve the grass cover and the weeds will decline. The little plant top right looks like Cardamine hirsutum, another common weed and one which spreads fast by seed.

Hmm, seems useful, assuming you can correctly determine the categories. My results were "No plants match the criteria"

It doesn't smell like celery - the closest scent that I can think of is a bit like chrysanthemum blossoms. I don't have a photo, but there is heuchera under the roses, basil was near, and also some columbine in the same bed. Christopher CNC, I just searched feverfew, and I do believe you are right! I suppose a bird or some other critter dropped a seed there (but who knows from where). Thanks!

Parietaria hespera? The leaf surfaces should be glandular and the leaves should have hairs around their edges(ciliate on the margin). They don't show up in the photo, but the succulent stems do. There's a lot of leaf variation in this species. Some individual plants have leaves that are acuminate, and some can be very oval,round shaped, but your plants have the more standard shaped leaves. If that's what they really are? Lol. I see that Pellitory of the Wall, P. juidaca is invasive in quite a few states over here, fortunately not mine. Doesn't everything imaginable grow on walls in England floral? You could get a lot more vegies by growing them on your walls.😂 I did envy your misty climate when I struggled with growing butterfy bushes. I would see photos of 16ft tall, lush bushes in England, and there would also be pictures of butterfly bushes growing in walls.🤣 I realized butterfly bushes aren't worth the trouble, but if I lived in a warmer climate I would possibly grow unique species of Buddleja. Is Buddleja invasive in England?