Great grey shrike?

Sighting date: 2023-12-26. 

Submitted by: Judith Townend. 

Location: Lazonby. 

Saw a bird on telephone wire, grey colouring, very long dark tail, it was against the light and no clear  view of the head. About the size of a blackbird

Not convinced it was a shrike but the tail was so distinctive and can’t think what else it could be. It definitely wasn’t a long tailed tit or a wagtail