The size looks too big for Puschkinia.
White bluebells was my first thought, but it's surprising to see a whole drift all in white.

I think its wild garlic, or Allium ursinum - can't confirm for sure because I can't see the leaves close up, but that's what it looks like. You can confirm for yourself by bruising the leaves, they'll smell like onions. Edible plant, pain in the neck in a garden...highly invasive.

Thanks for the ideas, the leaves are fairly
narrow and I didn't get a strong smell off them when I picked one and squeezed it, but I agree they certainly seem more of an oniony origin. Pretty sure they're not white bluebells as there are some of those further along - good thought though.

This is Allium triquetum, Three-cornered Garlic (Allium ursinum has much broader leaves and star-like flowers in clusters). It's a garden escape.

If you dig up a bulb, you will get a distinct whiff of onion. Don't let in your garden - it's invasive.

I agree that it is A triquetum, the flower stems are triangular in section like a toblerone. its pretty but not for a small garden.

I always call them white bluebells for want of a better name. Now I know differently though I did know it wasn't the true wild garlic that grows in woodlands as I've seen (and smelt) it many times.

Thank you all for your ideas, yes I think it must be A triquetum as I have seen it in a local front garden on my walks with the dog! A garden escapee, better in the forest where it looks pretty and does no harm :) and yes true wild garlic is very smelly especially when the dog runs through it !! Ha ha. Thanks again.

Whatever they are, they're gorgeous!