By the look of the cheek patches the cock bird is a mauve.
I can't see the hen's cheek patches clearly enough to tell but she is not an anthracite.
A mauve will have violet cheek patches and a navy blue tail
A grey will have blue or grey cheek patches and a black tail
An anthracite will have black cheek patches and the body will be dark grey
Slates are rare and also hard to indentify