The World of Tim Frazer

I remember this TV series well, being an impressionable 13 year old! It ran for over six episodes, something like 18-20. There were three stories, six episodes each but on Episode 7, the first story ended and the second story began, again for another six episodes with the third story beginning in the same manner. I still remember the shock when Barbara Day (Patricia Haines) was unmasked as the villain in one of the stories! It was very much done in the (radio) style of Paul Temple with Francis Durbridge employing the usual red herrings and co-incidences and the villain (in all three stories) being someone who was in the story often, usually a main character, who had a second secret name.