[cc]

Bloke wants the name. Might get pint out of it!

[adri]

Some sort of Iris?

[jaydig]

Dutch Iris?

[snowdrops]

Definitely an iris but as to variety you’d need a specialist grower to give you that

[sunshineband]

Does look like Dutch iris

[New shoot]

I'm going to disagree slightly and say Iris sibirica, possibly White Swirl, but I'm not 100% sure that is the correct variety. 

[sunshineband]

I'm going to disagree slightly and say Iris sibirica, possibly White Swirl, but I'm not 100% sure that is the correct variety.

Now I look more closely, I notice that the outer petals have a "spilt" in them, which is not typical of the hollandica varieties I have in flower in the garden, so points perhaps towards siberica, but I thought siberica petals were more rounded (and with a central split) but you're knowledge here is more far reaching than mine New Shoot.