Rule 55 was an operating rule adopted by railway companies in the British Isles in the late 19th century. It was introduced following a spate of accidents caused by signalmen forgetting that trains were standing on the line, sometimes within sight of their signal boxes.


Signal box inside

Inside a signal box on the Isle of Wight Steam Railway. Note the wooden collar on the third lever.

The rule required that, if a train was brought to a stand at a signal, within three minutes in clear weather or immediately in rain, snow or fog, the Driver of the train must despatch his Fireman, Guard or any shunter riding on the train, to the signal box to ensure that the signalman was aware of the presence of the train, and that all safeguards to protect the train, such as slides or collars on the signal levers, were in place, the crewman then signing the train register to confirm this.

In practice, this usually meant a fruitless trudge, often in foul weather, for the unfortunate crewman (although there was usually a mug of tea to be had in the signal box). Quite often the rule was obeyed only perfunctorily, the crewman merely exchanging a greeting with the signalman before signing the register and departing. In many cases, such as at major junctions or marshalling yards where crewmen walking along the rails were in grave danger from moving trains, the rule could not be applied properly. Further, the need for the fireman to return to the train would delay it if the signal was cleared in the meantime.


Failure to apply the rule properly was a factor in several railway accidents in the period from 1890 onwards. At Thirsk and Hawes Junction, the crews of the standing trains failed to carry out the rule. At Quintinshill, the fireman of the standing train signed the register although the necessary safeguards were not in place.

It is impossible to know how many accidents were prevented by the proper observation of the rule, and it could not always prevent a crash. At Winwick, a train was brought to a stand some distance from the signal box. The fireman left promptly to carry out the rule, but he had not reached the signal box before his train was struck. To prevent such occurrences, 'call plungers' (which operate an indicator in the signal box when pressed) or telephones were installed at some signal posts, or track circuits installed.

The modern equivalent of Rule 55 is module S4 of the Rule Book.


Diamond sign by Signalhead

A semaphore signal fitted with a diamond sign denoting exemption from Rule 55

A white diamond sign on a signal post indicates to the driver that Rule 55 does not apply at that signal (at which no telephone is provided), due to the train being protected by track circuits or similar means.

The 'Henry's Forest' Controversy

Henry was the focus of Rev. W. Awdry's irritation once again in the 1990s, when the third season of the television series was released. This series featured a number of original episodes that had not been adapted from the Railway Series stories, some of which annoyed Awdry with their lack of realism. The story that particularly angered him was called 'Henry's Forest'.

This episode begins by explaining that Henry's favourite place on Sodor is a forest through which the line runs. He likes to stop here and admire the scenery. A storm damages the forest, making Henry sad. The episode ends happily, with new trees being planted to replace the ones lost.

Awdry's complaints were directed at two aspects of the episode in particular. One was that it was unrealistic to have a railway running through a forest. Britt Allcroft, the series producer, countered by claiming that she had seen a number of lines that do just that.

The other aspect was that Henry stops to admire the view without alerting the signalman, which was in direct contravention of British Railways' Rule 55. This, Awdry argued, would never be allowed to happen in real life, and would be highly unsafe.

In the Season 5 story 'James & the Trouble with Trees' some trees are removed because 'The Fat Controller says they're too close to the line.' This is evident in Season 8 story 'Henry and the Wishing Tree', in which the trees are further back. It seems likely that these changes were a response to Awdry's complaints.