A strange flower in a garden devoid of flora

Strange Flower

Whilst out in the garden I was surprised to find this. Surprised mostly because our garden is utterly devoid of Flora with the exception of our neighbours Ivy and some weedy grass. No idea what kind of flower it is and never have I seen one like it before. The Stamen are shaped like some sort of Alien Helicopter and the flies seem to like it, as do the gnats. Otherwise it was just there, on it’s own

Recorded for posterity with the Tamron 17-50 F2.8 with a 12mm Kenko Extention tube attached.