There are already a number of St. Trinians films.
St Trinian's 2: The Legend Of Fritton's Gold (2009)
St Trinian's Versus The World
St Trinian's (2007)
The Wildcats Of St. Trinian's (1980)
The Great St. Trinian's Train Robbery (1966)
The Pure Hell Of St. Trinian's (1960)
Blue Murder At St. Trinian's (1957)
The Belles Of St. Trinian's (1954)