The delays happened on Friday at the height of the weekend rush, when a muck-spreading tractor broke through a fence at Bourne End, near Hemel Hempstead, Hertfordshire, slid down an embankment, crashed through signalling equipment and severed a power cable before coming to rest across all four sets of tracks.
The accident left 14 trains stranded between stations, trapping 5,000 people. Those on the Euston-to-Liverpool service were stuck in their carriages for six hours, and another 20,000 passengers were left waiting at stations along the line.
Anthony Williams, a former manager based at Manchester's Victoria Station, said that fragmentation of the rail service exacerbated the delays. Under the previous, fully nationalised system, a contingency plan would have been implemented immediately after such an accident, switching trains to other tracks and speeding up the recovery of services.
"The service might have been slightly delayed but you wouldn't have had the standstills we have had this time," he said yesterday.
Under the present system, Mr Williams said, the train-operating companies must sign contracts with Railtrack (which is responsible for tracks and signalling) before trains can be diverted onto lines the operators do not normally use.
"The operating service, in this case InterCity West Coast Ltd, will have had to pay track-access charges to Railtrack before implementing a contingency plan and moving trains onto other lines," he claimed.
InterCity West Coast agreed that such charges do have to be paid but added that it was "very unlikely" that plans to help free passengers were stalled while access charges were negotiated.
"I don't think for a minute that we or Railtrack would have waited to sort out the charges while passengers were delayed," said a spokeswoman yesterday.
However, Labour's transport spokesman, Henry McLeish, said the incident demonstrated the problems of "near-farcical proportions" being generated by rail-privatisation plans.
"If you take British Rail and split it into 95 parts," he said, "you are going to get fragmentation, you are going to get confusion."
BR admitted the clearance operation had not been ideal."I don't think anyone is going to say everything went smoothly, but we are satisfied we did all we could in a difficult situation," said a spokesperson.
The incident is likely to leave BR with a large compensation bill. It could have to pay out as much as pounds 625,000 to the estimated 25,000 passengers affected if they are refunded their full fares under the passengers' charter.
n The owner of the tractor that blocked the West Coast line last night apologised to the passengers affected.
Mark Gardener, of Boxted Farm in Hemel Hempstead, said the driver was in a state of shock over the incident.