Jack Hopkins (played by Michael Craig) is an aircraft designer with a passion for traction engines and he owns one called The Iron Maiden. His boss (played by Cecil Parker) is eager to sell a new supersonic jet aircraft that Jack has designed to American millionaire Paul Fisher (Alan Hale, Jr.). The first encounter between Fisher and Jack goes badly, and tensions only heighten after Fisher's daughter Kathy (Anne Helm) damages The Iron Maiden, rendering it impossible to be driven solo. Jack is desperate to enter the annual Woburn Abbey steam rally with the machine, but his fireman is injured and unable to participate. When all seems lost, the millionaire himself is won over by Jack's plight and joins him in driving the engine, and the two soon become firm friends.
After an eventful journey, Fisher and Jack reach Woburn Abbey and enter the rally, only for Fisher to injure his back at the last minute. When all seems lost, the sceptical Kathy appears and joins Jack in the engine. The two pilot The Iron Maiden from last place to first, winning the rally; at the finish line, Jack and Kathy embrace and kiss, while The Iron Maiden boils over and explodes. The engine is memorialised when Jack's new jet is named after it.
A Handley Page Victor military bomber is featured in the film as Jack Hopkins' supersonic jetliner. A number of sequences show a Victor in close-up, taxiing, taking off, climbing, flying past and landing with parachute deployed. These scenes were filmed at Radlett Aerodrome.Michael Craig as Jack Hopkins
Anne Helm as Kathy Fisher
Jeff Donnell as Miriam Fisher
Alan Hale Jr. as Paul Fisher
Noel Purcell as Admiral Sir Digby Trevelyan
Cecil Parker as Sir Giles Thompson
Roland Culver as Lord Upshott
Joan Sims as Nellie Trotter
John Standing as Humphrey Gore-Brown
Brian Oulton as Vicar
Sam Kydd as Fred Trotter
Judith Furse as Mrs. Webb
Richard Thorp as Harry Markham
Jim Dale as Bill
George Woodbridge as Sid Ludge
Ian Wilson as Sidney Webb
Brian Rawlinson as Albert, Village Constable
The traction engine that featured as The Iron Maiden was a John Fowler & Co. 7 nhp showman's road locomotive (works no. 15657, reg no. FX 6661). She was built in September 1920 as a class R3 road locomotive for heavy haulage work and saw many years' service on the Isle of Portland, hauling blocks of stone from the quarries to the harbour.
She returned to Fowler's works for conversion into a showman's engine, which entailed the addition of a dynamo bracket in front of the chimney, and a full-length canopy, among other things. Once converted she was based in Alfreton, Derbyshire, and undertook fairground work, until bought for preservation in 1952. From new she was named Kitchener – until the film was made, whereupon she was renamed The Iron Maiden.
The engine was first owned during restoration by John Crawley, the man behind its use in the production of the film. It was then sold to George Hawkins, before passing into the Dr Tony Marchington collection in Derbyshire, following its sale at the 1993 Great Dorset Steam Fair and became part of the same collection as Flying Scotsman, Nigel Gresley's world-famous LNER rail locomotive. The Iron Maiden is today owned by Graeme Atkinson, who displays the engine alongside a collection of other engines and fair organs as part of the Scarborough Fair Collection, at his holiday park in Lebberston, near Scarborough, North Yorkshire. The engine was featured on the cover of the Official Programme for the 38th Great Dorset Steam Fair, in 2006, and continues to make regular appearances at that event.
It has also made at least one appearance at the Yorkshire Air Museum at Elvington near York to be photographed next to the Handley Page Victor belonging to Andre Tempest that is preserved there.