Britain’s largest train company has launched automatic weekly fares capping, claiming the move will save some passengers up to £124 a week.

Govia Thameslink Railway (GTR) said it has introduced the measure for the 30,000 passengers who use its keyGo smartcard service for pay-as-you-go journeys.

The announcement means those passengers will pay no more than the value of a weekly season ticket for multiple journeys between two stations in the keyGo area, which covers the majority of GTR’s network.

Once they have reached the cap, all subsequent journeys for the rest of a week will be free.

GTR, which owns the Gatwick Express, Great Northern, Southern and Thameslink brands, believes weekly fares capping will benefit commuters unsure how often they will be travelling to their place of work.

The company said passengers making four return journeys in a week between Brighton and London Victoria could save £124, with a £65 saving for those travelling between Bedford and the capital.

GTR interim chief customer officer Mark Pavlides said: “Our simple tap-in, tap-out, pay-as-you-go keyGo system already guarantees our customers the cheapest walk-up fare of the day with none of the hassle of buying a ticket.

“The additional promise to never charge more than a weekly season ticket for travel between the same two stations means thousands of commuters returning to the office will never miss out on weekly season ticket deals, saving hundreds of pounds a week or month.

“And with automatically generated Delay Repay compensation claims, getting the best deal when travelling by train has never been simpler.

“With keyGo fares – applicable on our Key Smartcard – no matter how frequently you travel between the same two stations each week, you’ll never pay more than a weekly season ticket.”