What is this plant, please?

Self seeded tomato?

The leaves and shape of the plant are quite different from a tomato.
I think I need to take a picture from the side to show a better result.

Have you tried crushing and smelling the leaf? That might give you an idea.

This may be a better one.

It doesn't smell of anything much, I've just discovered.

I'm sure it's a weed; I get those in my pots/garden beds and pull them out, although I'm not sure what it's called.l

It could, of course, be some rare and beautiful plant but mine have gone into the garden waste.

I'm sure its a weed too.
I have a policy that anything which decides it wants to live in my pots can have a go.
I'm quite keen to try a nurture this one a bit, seeing as its lasted a little while.

I think it's a weed too..........and sorry to say, not a very pretty one!

I'm hoping it may sprout some berries or something.

DH nurtures things he isn't sure of, [usually weeds] but now and then turn out to be spectacular [but still weeds]
It looks a bit like cannabis to me MissA ! Crush it and put it in a roll up.

I've just noticed another one nestled amongst my fushias!
I think the leaves are rather nice, although I haven't smoked one yet!

a weed is just a plant in the wrong place.

I think it looks very much like an 'erb!

Deadly nightshade?

Oh I hope not! I've already nurtured a stinging nettle.
Its getting dangerous out there.

No, it's definitely not one you can smoke MissA
Don't try it!

I think it is Black Nightshade a member of the Potato and Tomato family, if you leave it it will have small green berries, don't let them fall or you will have lots more next year

Thank you, Diana and all.
When I searched for a similar image to try and work out what it is, tomato and nightshade both came up, so I shall leave it and wait for the berries.
Then it'll have to go, though.
I don't want all my pots full of them.

The flowers may help us to identify it, MissAdventure. Hopefully it will bloom soon.

It'll be interesting to see how it develops, now.
Hope it doesn't die off as the others have.

Looks very much like a tomato plant to me.

If you have these plants come up every year but they usually die back without flowering, where can the seeds be coming from? Very odd.

MissA I have an app on my phone called "PlantSnap" - it's quite amazing, you click on the app, camera icon appears, take a pic of the leaf or flower of a plant, and it scans a database and tells you what it is. Doesn't save the pics to my phone so that's a bonus. So far it works like a charm, I've tried it on familiar plants as control

Just ran your photo through the app and it came up with Black Nightshade.