Virgin Trains West Coast, which runs services through Cumbria and southern Scotland, has one of the highest records of significant delays, according to new research.
Passengers across the UK lost at least 3.6 million hours due to significantly delayed trains in 2016/17, consumer group Which? has said.
It also found that delays of at least half an hour affected 7.2 million passenger journeys.
Virgin Trains West Coast had 2% of its services run from 30 minutes to two hours late between April 2016 and March this year.
The company says 80% of delays are outside its control.
Virgin Trains East Coast had the highest proportion of significantly delayed trains with 3.7 per cent of its services run between 30 minutes and two hours late.
The research was released ahead of the 3.4% average fare increase on Tuesday.
Which? managing director of public markets Alex Hayman said delays suffered by passengers are "even more infuriating" when they struggle to claim compensation:
A Virgin Trains spokesman said: