As I had my garden rejigged this year. Lots of my labels blew away/disappeared. I have this fast growing but flowerless plant growing and for the life of me cannot remember what was in the pot last year. I’m now second guessing myself that anything similar was ever in it as I have spent my weekend picking weeds grown from bird seed spillage and my previously identified random potato plant surprise addition.
In the sticks near Peterborough
I don't think the ones in the photo are willow herb. Keep them watered and fed and wait and see what the flowers are like. If you don't like them, offer the plant to a friend or else pull it out before they have a chance to set seed and spread.
"We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw