The Harbour Master’s Mother is mentioned a few times in the series.
In the Season 2 episode Emily and the Rocket, he accidently calls her bossy on the phone when he meant to call The Oil Refinery Boss. The Harbour Master tried to explained to his mother what happened.
In the Season 4 episode, Theodore and the Lies, he jumped the gun when he told his mother he had sent her a parcel, before he realised he had run out of tape just the delievery van left. So he had to own up and deliver the parcel himself.
She was also mentioned in the Season 5 episode, Bedford's Big Move, where she sends him a box of tugboat cookies in the mail. At the end of the epiosde, the Harbour Master telephones his mother to thank her for her kindness.
Trivia
- Due to her son having a lot of offscreen family members, and since the Harbour Master turns out to also be a grandfather, this makes her a great-grandmother.