Possibly woody Nightshade, a member of the solanum family, don't eat the berries! I remove as it can be invasive.

Its most definitely NOT woody nightshade, that's a climber with different leaves and flowers.

I'm not sure what it actually is though - although the colour of the flowers with the yellow centre suggests a solanum of some sort, the shape doesn't particularly; seeing a flower bud would be more definitive.

Are the leaves soft or rather rough to to the touch?

That comes of my looking t the image upside down... thanks Bamboo.

I didn't want Portobello to panic at the mention of nightshade!

The leaves are fairly rough ..... it's wasnt very attractive until the little blue flowers appeared - I am thinking about taking it out completely ..... would it help if I posted a few more photos ?

When you get down to it there are no rules about what you should keep. Weeds are only plants in the wrong place. eg many people grow comfrey in the garden, but you'll find it in the wild flower books. Corncockle (now extinct in the wild) was a pernicious weed of cornfields but we grow it in our gardens for decoration.Annual poppies are a British wild flower and so are bluebells and honeysuckle - weeds? So if you like the plant keep some but if it takes over and is a pain dig it out.
It appears to have only three petals so I don't think this is a native wildflower.

If you could get them the right way up it would help.
Not easy though.
My guess would be Nicandra physalodes, Shoofly plant.

Thankyou one and all for your input ..... as it's a new garden I've just taken over I've already dug up a lot of plants that I didn't really think suited the space (it's very small) trouble is now I have quite a few gaps so I'm a bit reluctant to dig anything else up ..... on another matter I do have an excess of strawberry plants (fabulous fruits too) ..... if anyone is near North Oxfordshire they are very welcome to them.

It's not Nicandra, its unfuriating because I can't find out what it is, but if I do, I'll get back here. Hoping someone else will ID it in the meantime. There's something awfully familiar about the flower form...

I'm wondering about a herbaceous clematis.
Something like C. heracleifolia?

I've managed to download a photo of c. Heracleifolia and compared them side by side and it looks remarkably like it Landgirl. I wouldn't have had a clue!

My Goodness - you guys will not be beaten will you ? More importantly though ...... to keep or not to keep THAT IS THE QUESTION ?

I would certainly keep it, but if you don't like it, you don't have to! It's not really a weed, in fact it's quite expensive to buy, if my ID is right.

Thankyou Landgirl100 and everyone else with their help and advice - I have decided to keep it but half its size - if anyone has guidance on how to do that "properly" I would be eternally grateful.

Google it Portobello, there's loads of information on how to look after it and how big it gets.

I agree with Landgirl's identification, I have it in my garden. I prune mine back hard in early spring.