That looks like Arum. It's a native plant, and it produces a spathe in the summer and then red berries. There's a cultivated one with beautiful markings on the leaves - Arum italicum 'Marmoratum'.

These are easily pulled out if you don't want them in your garden.

I wondered about spinach. If so it will have a slightly gritty feel to the leaves and a greenish flower spike in summer. Don't try eating it until the id is confirmed.

Thanks. I think you are correct. I have just been out to compare with some others that I know are Arum's and these are just taller and slightly smaller more rounded leaves.
ValB

You're welcome. Glad to help.