Having built two of them over the years, I can tell you it is a model representative of a typical Thames river tug. It was originally maketed as a kit by Caldercraft, now taken over by Jotika, and named suprisingly enough, "Riverman"! Designed by the late Frank Hinchcliffe, as far as I am aware, not based on any particlur tug, just a general impression of the type. Hope this helps you.
Danny