Don't think it is Hazel or Birch but could be Lime..I'm just going by the shape.
Hope you get a proper answer.

Maybe a Datura seedling?

i think it is a Abutilon

It's not a datura...abutilon was one thing that sprung to mind as did Pauwlonia...they seed everywhere in my garden.

Are you sure its not a sunflower ??? lol

Thank you, George, I was thinking abutilon but couldn't think of the name!

Well I'm relieved there's agreement - I didn't really know what it was, just guessing...

I suspect that we are all making 'good' guesses at the moment, Bamboo. The seedling is still to small for certainty.

Thanks to everyone who has taken the trouble to reply to my plea for help. My main concern was that I might be growing something unsavoury, but your comments have put my mind at rest. It bears no resemblance to the sunflowers that I have grown, it could have been among the seeds or in the compost. I hope that it grows into something nice, it is already attractive.

Having looked at pictures on the internet I feel that what I have is probably a Pauwlonia.

looks like a plant i have just been given from a gardener, he told me it was a gourd.

Fairly certain it's not lime, Lilleybee (what a lovely avatar name!) and it's definitely not hazel or birch. I've got Pumpkin/gourd plants, and I don't think it's one of those, either, Gaz, and although I haven't got one at the moment, I seem to remember abutilon seedlings looking very similar, so If I'm allowed to put my guess forward, too, I think I'd go with that.