Potter has to give up his desk as it's needed in the Head's office for a new secretary. The staff are expecting a plain, middle-aged woman so they are shocked at the arrival of the glamorous and young Miss Knightley who is the "niece" of the Chair of Governors. She certainly turns the heads of the male staff and pupils but one male is particularly smitten - Mr Price. However it may be a short-lived affair as Miss Knightley is also hopeless at her job...
One of the better of the Series 4 episodes. It was quite common in that era for at least one episode of a sitcom to have a plotline around the arrival of an attractive young female character and "Please Sir!" was no exception and had done similar a couple of times before. While it wasn't a novel storyline it's still well-done. Miss Knightley may be good at garnering male attention and is a pleasant personality but she can barely type, is disorganised and has a limited work ethic. Her arrival at Fenn Street seems to be a "favour" by her "uncle" the Chair of Governors who had previously been seen with a different "niece" (played by Wendy Richard) early in the series. Her surname also seems to be a play on her lifestyle with her revealing that she is in male company every night!
The pupils have little role in this episode and probably by this stage and near the end of the series the producers realised it was wise to concentrate on the dependable comic performers - the staff. Mr Price - excellently played by Richard Davies - was always one of the highlights of the show and it's pleasing to see him centre stage here. He always had an eye for the ladies but this was really the only episode to centre on this aspect of his personality. His pride in his Welsh identity had always been present and is prominent here; the "Blodwyn" name being a reference to a crush of his when he was a boy. It's interesting to see that he and Miss Knightley do have a rapport and it isn't just a fantasy on his part but how far could their relationship go?
The female staff are less impressed by the newcomer. Miss Petting seems jealous - given her budding relationship with the Head she is worried that she will have competition. Typically Miss Ewell has more principled reasons for being unhappy with Miss Knightley - her incompetence - and she has to resort to doing the secretarial work herself.
Small subplots concern anniversaries for Potter and Miss Ewell (although she doesn't realise that any special day is forthcoming). Potter's birthday is imminent and typically he has hopes of the boat being pushed-out by his colleagues but will they be so generous? These themes are quite well-done and round-off an appealing episode.