Much different than how American shows go by Seasons, British shows go by what are called Series instead, and there was a two-year lapse between the previous series and this one.
Actually, this episode marks the second time Janice as a character appears, but it's the first time she's played by Robyn Addison, who'd become a regular cast member. In the previous episode from the previous season, Departure, Mowenna's blonde friend Janice is played by Katie Moore, who ironically teases Penhale for wearing a fake mustache, and the character (played by Addison) would later develop a romance with him.