Professor Popper's Problem[a] is a 1975[b] British children's science fiction comedy[15][7] film directed by Gerry O'Hara, starring Charlie Drake in the title role.

Akin to other CFF features of the 1970s, the film broke with the Foundation's earlier releases by accurately representing aspects of working-class Britain, albeit through a science fiction narrative.

In an elaborate bid to eradicate world hunger, he invents a shrinking powder, which when sprayed on vast food stocks facilitates a size reduction that allows for transportation by a single airplane.

[13][2] Their environment is greatly altered as a result; a book is now like a cliff edge, the rotary dial resembles a carousel, pennies are the size of hula hoops and a cat's paw is as large as a Ford Transit.

[22] Popper's colleague, Professor Crabbit (dressed in the attire of Sherlock Holmes), meanwhile sets about investigating what has happened to the cohort, arousing the suspicion of local man Rollins.

[3] Covert Russian operatives bent on industrial espionage and a London gang, the latter sporting two crooks sent to miniaturise the Bank of England and sell it to the United States in a suitcase, initiate their pursuits.

[26] Ian Millsted of Infinity magazine notes that CFF screenplays of the 1970s—including Professor Popper's Problem—remedied critiques of its features of the 1950s and 60s, which suggested "that they seemed to be set on an alien world where all the children spoke the Queen’s English [...], behaved with impeccable morals and were routinely smarter than any adult".

[27] According to Millsted, this was achieved by deploying "noticeably more regional accents and working class characters", relegating science-fiction elements to jovial plot points rather than intrinsic storylines.

[24] Edited by James Needs, Ken Hodges was responsible for the picture's photography, joined by George Provis as art director and Tony Hart on title design.

[15][1] Drake sang the film's theme, "I'm Big Enough for Me", opined by writers Ian Jones and Graham Kibble-White to be a quintessential "celebrity sing-a-long [...] the blessing of a star-led knees up".

Sidney Williams, Show Business Reporter for the Daily Mirror in May 1974, wrote that "[Drake] expresses the modest hope that audiences will be reduced only to laughter.

TV Cream affords a cynical synopsis: "[Drake] notes a worrying hole in his pension plan and promptly accedes to star in this tatty affair".

[35] Conversely, in an interview piece with Drake issued in April 1984, the Liverpool Echo opined the supposed triviality of the film to be a "red herring", the actor having targeted more theatrical roles.

[36] In this vein, film scholar Robert Shail favours Professor Popper's Problem for compensating unsubtle humour with "settings around council estates and comprehensive schools [that] were often realistically observed and facilitated audience identification", also commending the inclusion of "authentic working-class accents".