It also emerged last night that quick action by the express train's driver had averted a disaster.
A four-carriage local train, operated by the company First North Western, was standing on the "fast line" used by express services when it was hit at 8.52am by a Virgin West Coast train, 300 yards south of Winsford station in Cheshire.
Railtrack said the Virgin train, with 132 people on board, should have had a clear passage along the line.
"We will look into all potential causes," said joint statement from the three firms. "This includes ... the report that a North Western train passed a red signal."
The Virgin train was travelling at up to 110mph when its driver, Roy Eccles, saw the local train ahead.
In the seconds before impact, Mr Eccles, 56, applied emergency brakes and managed to release onto the track sand that is normally used to provide extra grip in icy conditions. Friction between the wheels and the track bought him vital extra braking power.
As a result, only his own carriage on the express was derailed, coming to rest - windows shattered - amid the local train's mangled rear coach.
Mr Eccles, who has 35 years' experience, jumped down from his cabin, hurting his leg, and, after ensuring that his conductor and crew were tending to passengers, walked down the track to apply clips which short- circuit the signals and turn them red.
One passenger, a soldier, Private Lee Topliss, 21, who had just flown back from Kosovo, said the train had been slowed to 50mph when it crashed. He said: "My ribs were sore, but I jumped off the train to see if the driver was OK. I saw that he was not in his compartment. I found him checking the carriages."
At first, paramedics were unable to remove casualties from the train because the power to the electrified line had not been switched off.
Some passengers climbed down to safety by ladders raised by fire crews, and ambulance helicopters carried others to hospital in Crewe. Some people suffered abdominal injuries. The force of the collision had thrust them into carriage tables. Others had whiplash neck injuries and scalds from hot drinks. No one was seriously hurt.
The Virgin "Wolf of Badenoch" express was eight miles north of Crewe and had gathered full speed when it approached the empty train destined for Manchester Piccadilly from Crewe.
In one of the semi-detached houses 50 yards from the track, Douglas Bailey walked across his lawn to see the wreckage.
"The next thing, the helicopter landed here in my garden. Everything happened pretty quickly afterwards," he said.
Mr Eccles, from north London, was later taken to hospital. "Richard Branson has spoken to him in hospital and [Mr Eccles] has said that he feels very embarrassed - that he is no hero and that he was just doing his job," said a Virgin spokesman.
It is likely to be some time before services between Crewe and Glasgow are resumed.
Passengers travelling from London to north-west England and Scotland for the next 24 hours can take alternative GNER services from London's King's Cross station. Midland Mainline services are also available from St Pancras.
Liverpool-bound passengers from London should travel from Euston to Crewe, and on to Chester, to pick up Merseyrail services. Other north-west services are subject to diversions through Manchester and delays. Services to Manchester via Stoke are unaffected.
Engineers hope to restore normal services by tomorrow. Passengers in doubt should ring the national inquiry line: 0345 484950.Reuse content