They certainly look like Alliums, i have some just like this growing at the moment.

Allium karatviense at a guess.

Whilst I agree with the probable ids, I don't see that they would 'mysteriously appear'. Please point out to them that I have a rockery and would they consider an appearance up here, please.

Tell them I have a rockery and wish they would disappear. Self seeders with a vengeance for us.

Well... Bulbaholic, Owdboggy. Owdboggy, Bulbaholic.

If they are flowering now they cant have just come from seed to flowering in one year. So did you not notice them last year?

nice plant though.

Thanks for the ID's, I think they do look like A.karataviense. I did buy a load of Alium bulbs but A.K wasn't one of them! I reckon that the bulb merchant has mixed some of these by mistake.