Kevin has sent me this fine photo of tug NER No 1 in Tyne Dock. She was built by Cox & Co (Engineers) at Falmouth in 1909. In this view she looks in almost pristine condition so date is probably about 1910. I have seen very few photos of this tug and all the others show her with access to the wheelhouse from the bow, rather than behind the bridge wings. I guess she was subsequently modified.
Compare this view with: http://www.tynetugs.co.uk/nerno11909.html
Also in the background is another Tyne tug HUTTON. See also: http://www.tynetugs.co.uk/hutton1893.html