Have a look at Meanie, she has just put a photo of a similar plant on her page which is called
Ornithogalum umbellatum - looks very similar.

Not sure, but is it Wild Garlic, try rubbing the leaves to see if your fingers smell of Garlic? or it could be the Star of Bethlehem? :o))

Looks like Cammomile's Ornithogalum, "Star of Bethlehem". It can spread and become a weed if you are not careful.

Thank you,Cammomile,I have looked at Meanies picture,and it looks very similar...Lady Essex,I don't think it is wild garlic,but I will give it the sniffy test ..although the leaves are very sparse,I had a job finding them ,amongst other foliage
Bulbaholic,I definitely haven't planted one of these,and I also noticed another lone flower about a foot away..so probably another plant..Do they close up at night? I can't see it from the window this morning..If it is a spreader,I don't mind,as it is in a suitable place,where I have other ground covering plants,but thanks for the tip..I rather hope it is,as it's so pretty,and thank you..

Morning Sandra, check out images of Zephyranthes candida, looks similar to your flower.

Good morning Shirley..I haven't heard of this one,but I will take a look ,and thank you..:o)

Sent you a PM Sandra .....

I've googled the one you suggested,Shirley,and they look so similar,don't they? I am stiil no wiser really :o) I have left a comment on Meanies blog/photo,to ask her advice as to what she thinks..thanks for your help ...and also for your PM..will reply soon..I'm off out for the day tomorrow,to Doncaster Racecourse..I'm not putting my shirt/blouse on anything..it's a freebie AGM for all retired golden oldies,who worked for the same company..the purse won't need to be opened :o)

Deffo Ornithogalum umbellatum. It's a spring bloomer from the Mediterranean area, whereas Zephyranthes is from South America (?) and is a late summer bloomer. Zephyranthes only has the one bloom per stem, Ornithogalum umbellatum has numerous flowers per stem.

Bulbaholic is correct that it can spread like billyo which I like! Probably a gift from the birds, and yes they close up as the temperature drops.

Thank you Meanie,that is exactly it,with more than one flower per stem..I love it too,and it is in a border where it has room to spread..I hope it does..The birds must be thanking me for feeding them :o) Thanks to all of you for your help..

Hope you had a lovely day at the races Sandra - btw Meanie is a male - lol!!!

oops,sorry Meanie..I don't always read profiles..thanks Shirley for putting me straight..I remember a long time ago when you were 'Catwoman'or more precisely Womancat ?how is the lovely Megan,anyway ? Lol.:o)..and today was good thanks..:o)

Oh dear - apologies Meanie - don't know why I assumed you were female!

Lol you two! He's too polite to put you straight on his gender! As for the lovely Megan - I've just driven OH to Worthing - came home to find her sitting on the lawn staring at a tiny Mouse! Megan is now indoors and the Mouse has been put to the back of the garden!

Two good deeds done already,Shirley..give yourself some brownie points :o)

Lol Sandra! I think I deserve a Gold Star too as I have just cut back some Ivy, many Snails lurking within it and put my hand through the trellis atop of the fence to pull back any stray bits from the garden behind ours! I have offered to go round and cut it off as the lady is disabled, but she says it's ok!