An evening Sleeping-Car and Mail train of the Great Northern Railway, running from London Kings Cross to Edinburgh Waverley hauled by Ivatt 'Atlantic' No 276 derailed, killing 14.

To the alarm of the postal sorters and the station staff who realised it was the Mail train, it sped towards Grantham North box where the points, which had a 15 mph (25 km/h) speed limit, were set against it.

The Board of Trade inquiry, conducted by Lieutenant colonel P. G. von Donop, concluded that "it is feared therefore that the primary cause of this accident must for ever remain a mystery.

On none of these occasions did Fleetwood consult a doctor, and since he made no call on the GNR's own sick-pay fund, the company did not require him to have any medical examination either while he was on leave or before return to work.

[5]) The fireman with whom Fleetwood was taken ill, Brooks, and the driver's mother-in-law (who lived with him and acted as his housekeeper) both testified that he only ever claimed to be suffering from recurring sciatica, but there was no official medical evidence to corroborate or expand on this.

Other drivers and officials of the GNR, and Fleetwood's mother-in-law testified that, while he drank alcohol, he had never been seen drunk at work or at home, and Lt Col von Donop concluded that Talbot's initial fears were based only on hearsay from unknown sources.

[10] Lt Col von Donop also considered whether the engine crew lost track of their position on a dark night and did not realise they were quickly approaching Grantham as the train picked up speed on a long downhill gradient.

A number of Great Northern footplate men testified that the approach to Grantham was unmistakable, and the investigator agreed (adding that even in the highly unlikely event that the driver was unsure of his position, signals were in any case set against his train and should have caused him to slow down).

[5] The report noted that "The primary duty of a guard is the safe working of his train, and neither of these men seems to have shown himself on this occasion equal to his responsibilities."

Although the Board of Trade inquiry did not broach the subject, and von Donop accepted evidence from Talbot's superiors that he was "thoroughly competent to carry out [his] respective duties",[17] other bodies stated concerns at letting unexperienced men act as firemen on express trains.

[17] These had included times travelling alongside a regular crew and acting as an inspector to record information about the running performance of the engines, a period spent examining brakes at York and times working as fireman on a variety of goods and passenger trains- a common practice on the GNR for engineering apprentices in order for them to gain practical experience of locomotive operations.

[18] These posts were usually taken by the most experienced firemen - often those already passed as drivers - who had many years of experience on the footplate and had built up detailed knowledge of the geography, features, lay-out and hazards of the routes they worked on.

[19] Mr. Bagely of the ASRS and Richard Bell both stated that a driver working with a 'gentleman apprentice' would not as freely instruct them or correct deficient performance as they would a regular fireman.