The Titfield Thunderbolt is a 1953 British comedy film directed by Charles Crichton and starring Stanley Holloway, Naunton Wayne, George Relph and John Gregson. The screenplay concerns a group of villagers trying to keep their branch line operating after British Railways decided to close it. The film was written by T. E. B. Clarke and was inspired by the restoration of the narrow gauge Talyllyn Railway in Wales, the world's first heritage railway run by volunteers. "Titfield" is an amalgamation of the names Titsey and Limpsfield, two villages in Surrey near Clarke's home at Oxted.

Michael Truman was the producer. The film was produced by Ealing Studios and was the first of its comedies shot in Technicolor.

There was considerable inspiration from the book Railway Adventure by established railway book author L. T. C. Rolt, published in 1953. Rolt had acted as honorary manager for the volunteer enthusiasts running the Talyllyn Railway for the two years 1951–52. According to British rail enthusiast and film historian John Huntley's book Railways in the Cinema (published by Ian Allan in 1969), T. E. B. Clarke actually visited the Talyllyn Railway in 1951 and spent two days learning about the tribulations faced by its volunteers. A number of scenes in the film, such as the emergency resupply of water to the locomotive by buckets from an adjacent stream and passengers being asked to assist in pushing the carriages, were taken from incidents on the Talyllyn Railway recounted in Railway Adventure.

The residents of the village of Titfield are shocked to learn that their railway branch line to the town of Mallingford is to be closed. Sam Weech, the local vicar and a railway enthusiast, and Gordon Chesterford, the village squire, decide to take over the line by setting up a company through a Light Railway Order. On securing financial backing from Walter Valentine, a wealthy man with a fondness for social drinking, the men learn that the Ministry of Transport will allow them a month's trial period, after which they must pass an inspection to make the Order permanent. Weech is helped by Chesterford and retired platelayer Dan Taylor to run the train and by volunteers from the village to operate the station.

Bus operators Alec Pearce and Vernon Crump, who bitterly oppose the idea and wish to set up a bus line between Titfield and Mallingford, attempt to sabotage the plans. Aided by Harry Hawkins, a steam roller operator who hates the railway, Crump and Pearce attempt to block the line on its first run, but the train forces its way through. The next day, they sabotage the line's water tower but they are thwarted by Weech and the line's supportive passengers. After Chesterford refuses to accept a merger offer from them, Crump and Pearce hire Hawkins to help them derail the steam locomotive and the passenger coach lent to the villagers by British Railways, the night before the line's inspection. Blakeworth, the town clerk of Mallingford, is mistakenly arrested despite trying to stop the attempt, and the villagers become disheartened, believing that their line will now close without any rolling stock or working steam locomotive.

Mr. Valentine visits Taylor, who suggests that they borrow a locomotive from Mallingford's rail yards. Despite being both drunk, they manage to acquire one, but accidentally crash it after they're spotted taking it. Both men are promptly arrested by the police as a result. Meanwhile, Weech is inspired by a picture of the line's first locomotive, the Thunderbolt, which is now housed in the Mallingford Town Hall museum. Upon securing Mr. Blakeworth's release, he helps them to acquire the locomotive for the Titfield branch line. To complete their new train, the villagers use Dan Taylor's home, an old railway carriage body, hastily strapped to a flat wagon. In the morning, Pearce and Crump drive to the village to prepare to take passengers, but are shocked to see the train waiting at the station. Distracted from his driving, Pearce crashes the bus into the police van transporting Valentine and Taylor, and when Crump lets slip that they have been involved in sabotaging the line they are promptly arrested.

With Taylor arrested, Weech takes help from Ollie Matthews, a fellow railway devotee and the Bishop of Wilchester, in running the Thunderbolt for the inspection run. The train departs Titfield late because the police demand transport to Mallingford for them and the arrested men. Despite a mishap with the coupling, the villagers help the train complete its run to Mallingford. Upon arriving, Weech learns that the line passed every requirement for the Light Railway Order, but barely. In fact, had they been any faster, their application would have been rejected.

Engine Driver Ted Burbidge, fireman Frank Green and the guard Harold Alford were not actors, but British Railways employees from the Westbury depot, located on the former-Great Western Railway main line from London to Bristol. Originally they were provided only to operate the locomotives employed in the film on location, but when Charles Crichton talked to them and realised they "looked and sounded the part", they were given speaking roles and duly credited.