999 and maeve thanks for ideas. Not spotted that RSPB page before. Body of bird too vertical ie like heron, shag, cormorant when perched for suggestions. Cormorant nearest on that aspect; brown immature in flight in one book looks reasonable but Kirkby Stephen is smack halfway from E or W coast

Goldcrest I reckoned from google images where some shown spherical as mine. Bird book pictures hopeless as shown bird shaped like a warbler. Firecrest should be out of area for River Tees acc to my books though I know things do get about more.
(First Egret I saw was on the Axe, south coast but supposedly continental. Now they're regular at Saltholme by the Tees Estuary.)