As it approached the Downhill tunnel near Castlerock, between Coleraine and Derry shortly after lunchtime that Tuesday it was derailed.
A police spokesperson said recent heavy rain was believed to have been responsible for a landslide which saw rocks and boulders land on the track and two adjacent public roads.
Twenty-one people, including the driver, had been on board the three carriages when they were derailed.
Six people were treated in the Causeway Hospital in Coleraine.
Two others were released after treatment. The driver of the train, who is the most seriously hurt, is being treated for leg injuries.
One of the carriages was forced onto the beach adjacent to the track
Ciaran Rogan said: “It could have been a lot more serious. Fatalities could have occurred not only on the railway but also on the road and we will be taking it up with the landowners of the land adjacent as to exactly what their management and maintenance routine was for the cliffs here.”
Meanwhile, East Londonderry MP Gregory Campbell said that more needed to be done to make everyone that comes into contact with the railways aware that such a thing could happen.
He said: “When we look at the scale of the problem here, we could have been talking about fatalities. Any measures that can be put in place, although it is difficult to legislate for this sort of thing, I am sure will be put in place immediately.”
The investigation which was held into the derailment concluded that if the driver had received a warning one minute earlier, the accident could have been avoided.
Gerald Kerr of Her Majesty’s Railway Inspectorate, found there were a number of management deficiencies in Northern Ireland Railways which were contributory factors in the accident.
Mr Kerr said: “The report concludes that rock falls from the cliffs at Downhill were foreseeable and that further rock fall will occur in the future which will pose a risk to residents and to a lesser extent road and rail users.
“It is clear that, notwithstanding the injuries sustained in this derailment it was only by chance that a much more serious incident did not occur.”
Mr Kerr added: “Whilst the risk of rock fall at Downhill remains I urge the various parties to work together and take effective action to reduce the risks of a further rock fall event causing injury.”
Welcoming the report Mr Rogan said: “The report concludes that this incident occurred as the result of many factors which combined over a very short period of time. Some of them (were) unforeseeable, some of them possibly improbable.”
He said Translink engineers who had assessed the sloping within standards applicable in Great Britain had concluded that no action was necessary.
Mr Rogan added: “I don’t accept we were complacent. The rock slope was assessed against the industry standards and no action was deemed necessary.
“Independent experts said that the incident was, and I quote, in practical terms ‘unforeseeable’.”
Mr Rogan concluded: “The inspector has made recommendations as regards altering the assessment procedures for things like rock slopes and we sign up fully to implementing those recommendations.”
Do you have any memories of the derailment? Do you have any photos of the incident? Get in touch, email: [email protected].
The photos from the News Letter archive accompanying this story are by Kevin McAuley.