British Transport Police and auditors for the Association of Train Operating Companies are investigating the appearance of forged train tickets issued through at least two websites. A similar problem has been reported by Trenitalia in Italy. Since there is a big chance that the culprits are not based in the UK it could be very difficult for BTP to catch them. However, it will be much easier to catch the passengers using them and these people may find themselves having to buy new tickets- and if it's a quiet day they may even spend a few hours helping BTP with their enquiries!

To avoid embarassment, if you buy tickets online make sure it is from a real agent. The best way is to use a link from the nationalrail.co.uk site or from a well established travel company. As long as you ask the right questions, all agents should quote the same price for any ticket. The "competition" comes in quality of service and whether they levy a service charge. Normally the only way to get a cheaper ticket will be through a company specific promotion where you can only travel with that company and usually have to buy the ticket direct from them. Or you may have to collect vouchers from newspapers or off packets.

If the site doesn't ask you for date and time of the journey don't use it - without that info even a genuine agent can only sell the dearest "Anytime" tickets.

Never, ever buy a British train ticket (other than a Britrail Pass) in a foreign currency. If you live outside Britain see the next paragraph.

Sites which offer the option to collect tickets from station ticket machines by using booking numbers are a good idea. If the machine gives you your ticket you know it's OK and if it denies all knowledge at least you'll avoid trouble on the train! This also avoids genuine tickets being lost in the post. You may need the card used to buy for the ticket to identify yourself to the machine. But make sure you will be starting your journey at a station that can do this.

If the ticket included a reserved seat and the seat has the correct reserved label on it when you get to it then you'll also know it's genuine.

If you buy up to 12 weeks in advance (but not any earlier) you can get "Advanced" tickets on many journies over about 50 miles. These represent massive discounts on "Anytime" fares but come with conditions that Ryanair could have written! Even though The Trainline is spending a lot of money advertising this all genuine agents ought to be able to sell them.

On many long journies not involving London there are no peak hour restrictions - so "Off Peak" tickets are valid anytime (and they said this was going to be a simpler system!!).

The best way to save money is to get organised and ask the right questions rather than risk using shady sources.