Unknown Object in Stourbridge, England Photograph

Stourbridge, England-I have sent you a number of my photographs lately. A lot of the anomalies could be explained away as dust particles, rain droplets, orbs, etc, but can someone please try and tell me what the object in the photograph below is?

Basically, I was taking photos of the clear evening sky, as I do regularly, and looking at the sky with one eye whilst checking my camera viewfinder with the other. I took a series of shots which were normal, however, in one shot the naked eye saw something, and my camera found the enclosed “thing” in the photograph.

Any idea?

Regards,

Col. Foster