London Midland says the issue over a shortage of drivers will soon be rectified, amid another week of delays for passengers in Northampton.
The operator announced last month that services faced cancellation on a daily basis, due to not enough trained drivers being available.
But it has now announced it is fully subscribed for trainee drivers, and they will start to become operational from December onwards.
A company spokesman said: “We envisage this temporary issue will be resolved from December 9.”
The announcement came during a week when London Midland passengers experienced more delays, not all connected to the shortage of drivers.
Yesterday morning, the fast line from Euston to Northampton was blocked due to a rail defect at Watford Junction, causing delays.
And on Tuesday, a suspected broken rail led to services from Birmingham to Northampton terminating at Rugby, while Network Rail investigated the fault.
The company has pledged to keep passengers updated with changes to its services. These are available at www. londonmidland.com/live, via Twitter on @londonmidland or by calling National Rail Enquiries on 08457 484 950.
Richard Brooks, commercial director at London Midland, said: “We apologise to all passengers affected and thank them for their continued patience. Our driver shortage has been caused by a vacancy gap and we are working hard to resolve this. In the meantime, we will give advance notice of any changes. We believe this will provide more certainty, enable better journey planning and improve the travel experience.”