Grey Blackbird??

Before tidying up the leaves and rotting apples at the foot of one of the trees in our garden, I noticed that whenever a group of blackbirds were feasting, they had with them what appeared to be a GREY family member. At first I thought it was an unusually pale female (and have been referring to it as 'her'/'she' ever since). 

Same size, moves like a blackbird, there is only ONE, and she is NEVER seen without the others! 

But upon closer inspection, there are distinct markings. 

I set up a camera and captured the below.

Can anyone help identify??



At the foot of the tree in the below image.

Here are two videos too. (The link will expire in 1 week!) https://we.tl/t-ZoLPCvuvAI

She's particularly aggressive! And loves chasing off the small birds (woodlarks?) you'll see in one of the videos. No other birds mess with her, including blackbirds, and she's definitely the boss!