might be a triteleia of some sort.
triteleia hyacinthina sort of matches.

Your plant looks like wild garlic to me.... most would say get rid of it quickly or it will take over your garden... but I think it's pretty!

Thank you for the suggestions! It's rather small for a tritelia and I certainly haven't planted one, but tis a good idea.
I think the wild garlic has a lot of small bulbils in the centre of the flower Queenie, rather than one large one - it was my thought too until I looked it up. It certainly isn't ramsons as the leaves are too puny and there's no garlic smell at all. I have a feeling you're right about removing it but I think I'll give it a full season and see what happens.

triteleia hyacinthine is only about 8-16 " tall. one of its common names is 'fools onion' [no slur intended stera] It does look a good match have a google.

Fool's Onion - wow, that sounds just right! And explains why no garlic smell too. If the cap fits...
Thanks SBG. Do you know if its a quick spreader? I wonder where it came from. Its quite pretty and I would be happy to keep it if it isn't going to seed everywhere.

I don't know . if it is like the others in the genus then it wont be a thug like A moly.

Thanks - I'll leave it and see what happens.