London TravelWatch, which looks after transport users in the London area as well as stations from Bedford to London, says travellers can save pounds by buying a cheap-day return to Redhill in Surrey.

Two months ago train operator First Capital Connect (FCC) introduced the ban on holders of cheap day returns on services running northbound from London between 4.30pm and 7pm on weekdays.

London TravelWatch chairman, Brian Cooke said: "We noticed that owing to the hurried and confused way these restrictions were introduced, that a very important exemption was still available. We advise passengers to use this method in order to pay significantly less for their journey. By buying tickets to Redhill, passengers in Herts and Beds can save a considerable amount of money."

Four adults travelling from St Albans and using a "Groupsaver" ticket to Redhill would pay just £20 compared to £58 for standard day returns to London.

One person would pay £10 for a cheap day return to Redhill compared to £14.50 for a standard day return.

From Harpenden the standard day return fare to London is now £18.80 while the cheap return to Redhill is £14 and the "Groupsaver" for four is £28.

Mr Cooke said: "We are pleased that we have identified these savings for passengers and we hope they will benefit from them. The fact that FCC didn't pick this anomaly up when they introduced the new regime merely highlights how chaotic and un-thought-out these restrictions were.

"The fares system on the railways is confusing without the train operators muddling it even more for passengers. As we said when the restrictions were announced, they are a real dog's dinner and not the answer to overcrowding."

FCC did not dispute that the loophole discovered by London TravelWatch's did exist. However managing director Elaine Holt said: "If customers want to travel outside peak times on both their outward and return journey, the Cheap Day Return to London remains the best value.

"For the St Albans to London example quoted by London TravelWatch, the Cheap Day Return is £7.90 compared to the Cheap Day Return to travel further to Redhill which is more expensive at £10."

She said no-one disputed that one of the main issues facing FCC was severe overcrowding on northbound evening peak trains out of London.

And she insisted the restrictions were introduced to try to spread demand away from peak trains.

The company is working with the Department for Transport to try to improve capacity on the Bedford to Brighton line.