Camilla Fritton's dog, Mr Darcy, is named after a Jane Austen character from "Pride and Prejudice" (1995), as played by Colin Firth in the 1990's adaptation
The picture in Miss Fritton's study is a painting of Alastair Sim, as he played the original role in the original films. The bust that is destroyed by Annabelle's hockey blow also has the features of Sim.
When Colin Firth first makes his inspection of St Trinian's, and is tossed out of the Posh Totty's window, he walks to the hockey field wet, in a white shirt with his jacket over his arm. This is reminiscent of the part he played in the 1990's mini series "Pride and Prejudice" (1995), where he does a scene in the exact same way as depicted here.