Real conundrum here - Clydebuilt ships database only has one tug named Goliath built by Simons, and that was in 1946 as originally ordered as "Empire Tessa", renamed "Eminent", then much later as "Goliath". She does look very like the M731 Triang tug - but she was only 116ft rather than the near 150ft of the model.

Scanning through "British Steam Tugs", I can't find any 150ft tugs that look much like the M731. I suspect a lot of "artists' licence" was applied to the Triang design.

Looks OK though doesn't it...