Hello Neale
Yes i think they had all new tugs around that time built to replace these lovely tugs.

She is in the colours of Tees Towing Co. Ltd. for whom she was built. Tonnage 214 (Lloyds), Company was owned by William Crossthwaite & Son and was also known as Cross Line Tugs. In 1990 it became part of the Cory Group but the tug had been disposed of by then sometime between 1985 and 1988 by the look of it. A namesake was built in 2000 as part of the Svitzer empire