Rather hard to tell but check out HerbBennet (aka Wood Avens, aka Geum urbanum.

could you take a picture of it in situ so we can see the way it grows.
Doesnt look like wood avens as it seems shiny.

Can’t take another picture because I’ve thrown the plants in the garden refuse bin. The urn, which was going to be planted up again, was full of these little plants. They came out very easily and wilted quickly. I wondered about ground elder but since I’ve not had experience of it I can’t tell.

I’ve just looked up Herb Bennet and it seems the most likely answer. The urn is in a shady fairly moist border. Anyway, unless proved otherwise that’s what it’s going to be!

Thank you for you help.

I was pretty sure as I'm plagued with it at present.If you let it flower the flowers should be small and yellow.