What am I?

A stroke of luck to see this little bird and 2 other mates in the garden this afternoon. I had the longer lens on the camera by chance and was able to capture this through the non too clean kitchen window. 

I tried looking it up in my bird book, but it didn't match up with any of the pictures. I had called it a long tailed tit, before I put my glasses on, but it's not. I haven't seen one of these before.

I've put 2 more views in extras as this angle doesn't show the length of his tail. 

Can anyone help me identify it? Please :0)

A really cold day.