Question: Which of the following films is a documentary about a London, Midland, and Scottish Railway mail train: Night Mail or What Would Jesus Buy?

Context articles: Wreck of the Old 97
Brian Field
George Bangs
Stafford rail crash (1996)
Air Mail Facility
Night Mail
What Would Jesus Buy?
Railway Mail Association
Railway mail service library
London, Midland and Scottish Railway

The Wreck of the Old 97 was an American rail disaster involving the Southern Railway mail train, officially known as the Fast Mail, while en route from Monroe, Virginia, to Spencer, North Carolina, on September 27, 1903.
 Due to excessive speed in an attempt to maintain schedule, the train derailed at the Stillhouse Trestle near Danville, Virginia where it careered off the side of the bridge, killing eleven on-board personnel and injuring seven others.
 The wreck inspired a famous railroad ballad, which was the focus of a convoluted copyright lawsuit but became seminal in the genre of country music.
Brian Field (15 December 1934 – 27 April 1979) was a solicitor's clerk who was one of the masterminds of the 1963 Great Train Robbery.
 He was the crucial link between the key informant known only as ""Ulsterman"" (who came up with the idea of robbing the money-laden night mail train and also provided the details of the schedule and contents of the trains) with the actual gang capable of planning and carrying out such a complex and large scale robbery.
 He was found guilty of Conspiracy to Rob but his conviction was later overturned on appeal.
 Field only served time in prison for Obstruction of Justice in relation to arranging the purchase of Leatherslade Farm, near Oakley, Buckinghamshire which was used as the gang's hideout.
George Bangs (February 28, 1826 – November 21, 1877) was an American who developed the railroad mail car and was the General Superintendent of the Railway Mail Service from 1871 to 1876.
 He was also an advocate of "fast mail" and, in his 1874 report, he reported the need for a fast and exclusive mail train "designed to expedite the movement of mail from the east to the west and cover the distance in about twenty-four hours".
 In March 1869, George Buchanan Armstrong, the then-superintendent of the Railway Mail Service, moved to Washington, D.C. and Bangs was made assistant superintendent until replacing Armstrong in Washington, D.C. upon Armstrong's death in 1871.
On 8 March 1996, a Transrail freight train travelling from Mossend in Glasgow to Willesden in London, derailed after an axle on a wagon carrying liquid carbon dioxide failed due to fatigue at Rickerscote 2.2 km south of Stafford.
 Almost immediately after the derailment, a Travelling Post Office mail train hauled by a Rail Express Systems British Rail Class 86 electric locomotive (no 86239) collided with a section of the derailed freight train on the adjacent line and fouled the path of the TPO mail train.
 One person, a mail sorter, was killed in the crash and twenty others including the driver of the mail train were injured.
With the establishment of the first air-mail route in 1918, and the later additional routes, plus the accepted use of premium priced air mail by the public, it was only natural that the Railway Mail Service (RMS), being in charge of transit mail, was assigned the task of establishing "Air Mail Field" (AMF) postal facilities at the major airports.
 Only outgoing air mail was distributed at these workrooms, channeled there by both the post offices and Railway Post Office (RPO) routes.
 This mail was distributed and dispatched to other AMFs via the different flight connections.
 Incoming mail from other AMFs was distributed by general scheme and pouched to outgoing RPOs and necessary post offices.
 The Motor Vehicle Service provided frequent trips between the city post office and the AMF for air mail ground transportation.
 In 1951, there were 1200 clerks manning forty AMFs.
 They continue to exist within the U.S. Postal Service (USPS) and are now called Air Mail Centers (AMCs).
Night Mail is a 1936 documentary film about a London, Midland and Scottish Railway (LMS) mail train from London to Scotland, produced by the GPO Film Unit.
 The film ends with a "verse commentary" by W. H. Auden, written for existing footage.
 Benjamin Britten scored the film.
 The film was directed by Harry Watt and Basil Wright, and narrated by John Grierson and Stuart Legg.
 The Brazilian filmmaker Alberto Cavalcanti was sound director.
 The locomotive featured in the film was Royal Scot 6115 "Scots Guardsman", built in 1927.
 The film has become a classic of its own kind, much imitated by adverts and modern film shorts.
 "Night Mail" is widely considered a masterpiece of the British Documentary Film Movement.
What Would Jesus Buy?
 is a 2007 documentary film produced by Morgan Spurlock and directed by Rob VanAlkemade.
 The title is a take-off on the phrase "What would Jesus do?
".
 The film debuted on the festival circuit on March 11, 2007, at the South By Southwest (SXSW) conference in Austin, Texas.
 It went into general U.S. release on November 16, 2007.
The Railway Mail Association (RMA) was originally "The National Association of Railway Postal Clerks" when chartered under the laws of New Hampshire in 1898 as a fraternal beneficiary association.
 In 1904 the name was changed to the RMA and lasted until 1949 when the Post Office Department renamed the Railway Mail Service as Postal Transportation Service.
 At that time, it became the National Postal Transport Association.
The Railway Mail Service (RMS) Library is a major collection of materials pertaining to en route distribution history.
 Incorporated in May 2003, it can assist researchers interested in Railway Mail Service, route agent, Seapost, Railway Post Office (RPO), and Highway Post Office (HPO) history.
 The collection has many unique, original-source documents that provide answers to questions dealing with the transportation and distribution of USA Mail between 1862 and 1977, as well as other countries during the 19th century and 20th century.
The London, Midland and Scottish Railway (LMS) was a British railway company.
 It was formed on 1 January 1923 under the Railways Act of 1921, which required the grouping of over 120 separate railways into four.
 The companies merged into the LMS included the London and North Western Railway, Midland Railway, the Lancashire and Yorkshire Railway (which had previously merged with the London and North Western Railway on 1 January 1922), several Scottish railway companies (including the Caledonian Railway), and numerous other, smaller ventures.