This is springing up at various points along our fences. The neighbours on one side have completely paved their garden, and I can see no sign of the plant growing on their side of our shared fence. I don't know the neighbours on the other side very well, and don't feel comfortable asking if I can examine their garden! So I don't know if it's growing there, but certainly can't see any sign of it growing along the top of the fence.
Does anyone recognise it please?
EDIT: Sorry about the typo in the thread title!