[Spuckler]

  To save me time consuming research,  can anyone identify this plant please? It's in the centre & bottom right of the pic attached.  It first appeared on my plot last Spring & has gone berserk over autumn & this winter.    Thanks.

[Gardener and Rabbit]

Centre & bottom left, they're seedlings of rosebay willowherb.

G&R

[Aunt Sally]

Centre & bottom left, they're seedlings of rosebay willowherb.

G&R

I agree !

[Spuckler]

Thanks both for your response. Following your ID I searched it on the tinternet and found - two willowherb seedling pics!  The pic of the smaller seedling is the rosebay willowherb you mention & the larger pic is of broadleaf willowherb.  Which one do you think is the one in my pic?  I favour the broadleaf.  Thanks again.

[Yorkie]

The one on the right seems to have shinier leaves

[jezza]

Hello definitely Willow herb,need to get it out or it will take over roots can get as thick as a finger   jezza