Streptoplia Risoria?

I think the two sleek critters that have started haunting the bird table are barbary doves. They could be collared doves, but they don't have the wing markings.

Oh my goodness, they're having sex on the back wall!

According to the Collins Guide to British Birds (1986) barbary doves are "frequent aviary escapes, and are breeding ferally in N. Lancs"

Seems like they could be breeding ferally in S. Lancs now.