Later, the iron lung maker, is demonstrating his equipment in the middle of a seaside beauty contest, and tells the story of the gift of the magnet to the crowd, slightly embellishing for effect.

On a train returning to school, Johnny sees the little boy's nanny and overhears her telling her friend about her budgerigar, which she says has died of a broken heart.

He is again startled by a policeman and hides in the back of a Jacob's cream crackers van, which takes him to the Liverpool slums, where he comes into conflict with the local boys.

[4][5] James Fox (then known as William) had appeared in The Miniver Story earlier in the year, and this was his first starring role, at the age of 11;[6] his performance was largely appreciated, being described by the British Film Institute's reviewer as "certainly lively enough as the over-imaginative Johnny".

[4] Stalwarts of Ealing's repertory ensemble, however, such as Stanley Holloway and Alec Guinness, were absent, although James Robertson Justice made a small appearance as a tramp, using a Gaelic pseudonym;[7] at the time he was a candidate in the General Election.

[8] The Monthly Film Bulletin wrote: "The plot of The Magnet is not allowed to develop naturally, but is carried through a whole series of improbable coincidences and misunderstandings.

The attitude to children, too, is less natural than determinedly avuncular and whimsical, and Charles Prend has been unable to make William Fox (Johnny) appear very much of an actor.

The same artificiality is apparent in the film's humour; the story departs from the adventures of the child to include a number of conventional jokes at the expense of such familiar targets as psychiatry, domestic difficulties, and the Labour Government.

"[11] The British Film Institute's reviewer criticised it as "somewhat burdened by cumbersome moralising and too many credibility-stretching coincidences and misunderstandings" and described it as "an attempt to revisit the success of Clarke's earlier Hue and Cry".