Intriguingly (to me) there is absolutely no indication that the swing bridge was about to be opened to allow passage for the seemingly fast-approaching paddle tug and barges!?
and why not? Funnel looks about right. I wonder when the photo was taken? Posted in 1910, taken in 1905(ish). If so and RR is correct the tug would be one of BEN LEDI, DARING and THAMES.
Not the twin-funnel DARING (per your Tyne Tugs site) nor does it seem to match the BEN LEDI you also have illustrated. That would seem to leave the THAMES??