Dr Hogg's original secretary, Pearl (Jacki Piper), left at the end of episode Episode #1.7 (1975) to get married and live in Hong Kong. A new secretary, Colette (Wendy Richard), started in Episode #1.8 (1975), but Dr Hogg was so absent-minded that he still called her Pearl, and this is how she was listed in the credits for all the remaining episodes.