About the same size or slightly bigger than a crow, either black or very dark brown with a white neck and underside. Long wings when flying which are mostly black/brown but the last inch or two of wing feathers is white, so a long white stripe along the length of the wing. Haven't been able to get close but I think I can make out an orange beak.

This bird seems lost and has been following and chasing the crows that are usually in the field but they keep flying away and this bird keeps following them.

Location is the Marconi field, next to the coastal path, next to Poldhu Cove, Lizard, Cornwall.

I've looked at many bird identifier databases but can't see this bird anywhere. any help much appreciated.