The New Avengers, Series 1 - Episode 10
by Brian Clemens
Directed by Graeme Clifford
The original TV Times listing for Gnaws credited Anulka Dubinska as "Pretty Girl" - and credited Peter Richardson and Denise Reynolds as "Couple in car", but no such characters appear in the episode; I've tracked them down in this episode. They may be among the test subjects at the beginning of the episode as well.