TRAIN operator First Capital Connect has been obliged to use older trains on its Great Northern services to Huntingdon and St Neots because of two recent accidents.
The first, in July, involved a camper van overtaking a line of traffic at a level crossing in Littleport.
The second, on Sunday near Kings Lynn, involved a collision between a tractor and a train. It caused extensive damage to the front of the train, as well as demolishing two overhead electrification masts.
"In the past two months we have experienced two collisions, which have resulted in a stock shortage while these trains are being repaired," a spokesman said.
"As a result, we have had to bring older units into service. These trains will eventually be replaced as part of the £6billion Thameslink programme.
"On behalf of FCC I apologise to our customers for this situation and I can assure them we are working as hard as possible to repair the damaged trains as quickly as possible."
Damage to the train in the tractor collision was so severe that it could take up to six months to repair, the spokesman added.
Passengers have complained about the service to Huntingdon Town Councillor Nigel Pauley, who is a regular traveller and who claimed that trains introduced two years ago to add to capacity were 30 years old.
They were actually built in 1989-90 and were refurbished before entering service on the Kings Cross-Peterborough line to operate as 12-carriage trains in the peaks.
"Our relatively modern trains have now been replaced on this journey by creaky old rattlers," he said. "They are noisy, crowded and uncomfortable."