An urgent overhaul of Britain’s rail fares system is required after analysis revealed “absurd inconsistencies”, a charity said.

Savings from travelling at off-peak instead of peak times range from zero (from Pontypridd to Cardiff) to 57% (from Brighton to London), a study of 16 popular routes by the Campaign for Better Transport found.

Among the journeys sampled, the cost per kilometre of flexible day return tickets varies from as low as 15p (from Newquay to Plymouth) to as high as 62p (from Chelmsford to London).

The study, shared with the PA news agency, also found buying a monthly season ticket instead of four anytime return tickets per week for four weeks ranges from being 20% more expensive (from Grays to London) to 43% cheaper (from Brighton to London).

Campaign for Better Transport campaigns manager Michael Solomon Williams said: “The rail fares system is riddled with absurd inconsistencies which makes buying a train ticket time-consuming and complicated, creating a real barrier to train travel.

“The Government has talked about reforming fares for years, but aside from a little tinkering around the edges we’ve seen nothing like the root-and-branch reform promised.

“A simpler, fairer, easier and better-value fares system is now long overdue.”

An ambition to “simplify the confusing mass of tickets” was announced as part of wider rail reforms in May 2021 by then-transport secretary Grant Shapps in a White Paper.

The Williams-Shapps Plan for Rail was based on the recommendations of a review carried out by former British Airways chief executive Keith Williams, which was established in September 2018.

Making single fares half the cost of a return – known as single-leg pricing – on LNER services is among the few major changes introduced since then.

The Department for Transport (DfT) also funded the rollout of contactless pay-as-you-go ticketing to 53 more stations in the South East this year and pledged its support for trials of the system in Greater Manchester and the West Midlands.

Regulated fares – which include season tickets on most commuter journeys, some off-peak return tickets on long-distance routes and flexible tickets for travel around major cities – will increase by up to 4.9% in England on March 3.

A DfT spokeswoman said: “We have just announced a significant Government intervention to cap rail fare rises at 4.9%, considerably below the 9% of July’s Retail Prices Index figure, on which these rises are historically based.

“We are also delivering simpler, more flexible and better-value train tickets for passengers by rolling out contactless pay-as-you-go ticketing and single-leg pricing to ensure that passengers get the best value for money.”

A spokeswoman for the Rail Delivery Group, which represents train operators, said: “We support the need for fares to be made easier and more flexible.

“Our extensive fare consultation in 2019 overwhelmingly demonstrated the need for modernising rail fares.

“We will continue to focus on creating a simpler, better-value fares system for our customers and enhancing the overall passenger experience.”

The Scottish Government announced last week that all ScotRail fares will rise by 8.7% on April 1.

No decision has been made on fare rises in Wales.

Fares in Northern Ireland are set by operator Translink.