first thought was rosebay willow herb. but is that a blue/purple flower bud in the bottom one?

The purple flower has just fallen off the verbena bonariensis. Will look up Rosebay Willow Herb

leaves are looking too shiny to my mind. Do you have sweet rocket [Hesperis matronalis] in the garden? looks a bit like that too.

Evening primrose? Oenothera erythrosepala (I just looked up its Sunday name)

If it is pink or purple it stays, if its yellow it goes ;-) Will see what it turns out to be. thanks for the info, at least I know what to look out for.

I'd say it was oenothera biennis. You'll get pale yellow flowers on five feet tall stems next year

Possibly, but biennis is less common. Hybrids are common though, so just go for evening primrose! They are yellow but quite pretty - I let them stay and try to pull them up before they seed.