What are these bird droppings?

[BecauseMyRingBurnsSheila]

I've never seen them before and they are ALL OVER my conservatory! Identification would be really helpful please.

Does anyone know?

Possible pied wagtail that has spent some time looking at its own reflection. They do that sometimes, either fighting or trying to mate with their own reflection, and leave a right mess.

Or baby swallows perched on a higher level or wire and its dropping down.