In the film Las hijas de Drácula (1971), her character is executed by being burned at the stake. The stunt was performed by Matheson herself, with no special effects or stunt double. There was also a Fire Safety Officer present on the set for everyone's safety. Ironically, Matheson has stated that instead of being nervous over performing a potentially dangerous stunt, she was more excited about the fact that she was working with Peter Cushing, whom she had great admiration for.
[on Lynne Frederick] She was totally lovely. We were once marooned in a shared hotel room in The Hague for three weeks. Hardly the stuff of stardom, as we moaned at the time. We were waiting for producers to 'produce' the money to make a film that never materialized. We had fun though, she was delightful company.