Hello,
welcome to birdforum! Do you have more pictures?
I agree with you, heavy artefacts alters general jizz and details of this bird, making it hard or impossible to identify. Artefacts must be prevalent in your picture, because I am not aware of an european bird that looks like this (or is it indeed an exotic species. Than I am out).
I must admit, my first feeling was Spotted Flycatcher, but thats a much smaller bird and tail is to long for this, rusty-brown head is also wrong.
And I cant convince myself seeing a Cukoo in this bird, although trying hard. Same with a Dove/Pigeon, as a juvenile Stock Dove came into my mind., but tail is to narrow (passerine-like) ... I am puzzled.
Was the size compared to the mobbing Crows.? Not meant as an offense, this might not be clear to you as a new member, but I want to get an answer to your bird, and I am puzzled.
Did you take this picture through binoculars or a scope? If yes, than disortion caused by non-parallel binoculars and cameras might well result can change proportions of your bird,so I ask for more pictures.
Edit: had written this some minutes before, then read the answer of the Fern, and realised, that I assumed too, that it was taken in Bath, therefore UK