The Guinea Pig (U.S. title The Outsider) is a 1948 British film directed by Roy Boulting and starring Richard Attenborough, Sheila Sim and Bernard Miles.

The "guinea pig" of the title is 14-year-old Jack Read, a tobacconist's son who, following the Fleming Report, is given a scholarship to Saintbury, an exclusive public school.

[10] The Monthly Film Bulletin wrote: "The photography is good, and the sets are so realistic that one can almost smell the school atmosphere, and it is difficult to believe that Saintbury does not really exist.

According to Crowther, "the details are highly parochial, the attitudes of the characters are strangely stiff, the accents and idioms are hard to fathom—and the exposition is involved and tedious".

Wallowing in the clichés of establishment privilege, director Roy Boulting makes few demands of a cast that almost sleepwalks through familiar characterisations.