Thought at first it was one of the sow thistles, but the leaves are wrong for that. Replying to see the answers.

Bolted radishes?

Don't think so Darren. I don't eat radishes. thanks

I would have said that it was a sewan - local dialect for a sow thistle. Does it have a square stem with a white sap when damaged? Generally considered to be a field weed.

Definitely a weed. Pull it out and bin it before it seeds all over.

it looks like common sowthistle [Sonchus oleraceus] as it isn't spiny leaved. it is certainly classed as a weed or Native wildflower.

Thanks Everybody. It's gone.