Celia Green is Mrs Pickwell's replacement as Deputy Headmistress after Pickwell's (faked) death. It is quickly revealed that Fraser hired her because he thought she was the British rapper Professor Green, and she retains the nickname "Pro Green" in tribute. When Alfie and she first met, she came across as very friendly, but in reality she was just as strict about the school rules as Miss Pickwell was, with Alfie even at one point saying that he preferred Pickwell. Later in the episode, she ended up sleeping with Alfie's Dad, Martin (whom she went to teacher school with), when he invited her over to Alfie's apartment for a Valentine's Day dinner. She continued to act like a dictator, and continued her relationship with Martin, often tormenting Alfie with it. She became increasingly extremely obnoxious, pompous, sanctimonious and derisive, taunting other staff in insensitive ways. She also saw herself as a higher category of importance than anyone else, questioning why she should suffer for the school's 'profligacy', when she flaunted her own state of profligacy and ensured that she was the only person to benefit from the situation. In the Series 2 finale they got engaged. She is absent from the Christmas special due to her and Martin being on their honeymoon, but by the first episode of Series 3, she left Martin and took his money, causing Martin to live at first in his car, then alongside Alfie and Rosie.

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