Virgin Trains says it has permanently removed all peak-hour restrictions to trains that travel on Friday afternoons from London Euston station.
It said the decision was made to ease overcrowding on Friday evening off-peak trains to destinations such as Birmingham, Manchester and Liverpool.
Passengers on off-peak trains are often forced to stand for hours in order to avoid paying much higher peak fares.
Transport watchdog Transport Focus said it welcomed the move.
Customers can now choose to travel any time in the afternoon, and they will be charged off-peak ticket prices.
“Virgin deserves praise for testing a real practice improvement in the service they offer hard-pressed passengers, and for following through to make a permanent change when demand clearly speaks for itself,” Transport Focus’ chief executive Anthony Smith told the BBC.
“Virgin’s experience suggests some clear lessons for other operators too – we do hope others do not wait long to follow suit.”
Previously, a return ticket from London to Manchester that was bought on the day and valid for peak travel would cost £212.45. In contrast, an off-peak return fare costs £86.90, without having to book in advance, giving a saving of £125.55.
However, customers can still get cheaper prices on train tickets should they choose to make an advanced booking.
Virgin says that the off-peak return fares on Friday afternoons offer savings on the following destinations: