Most train operating companies (TOCs) have altered their penalty fare policies and have removed many Permit to Travel machines.
The machines, which closely resemble those found in pay and display car parks, were manufactured by Almex Control Systems.
[1] Machines were given the designation AS-9 (wall-mounted) or AS-88 (mounted on a metal base), but internal workings and tickets were identical in each case.
A button is pressed to print the permit, which shows a serial number, the station name, the date and time.
Because any amount of money on a valid Permit to Travel will ensure that a passenger cannot be charged a penalty fare, it is entirely possible (if the passenger is not encountered by an inspector, who will sell a full ticket) to make a two-hour train journey for as little as five pence (the lowest denomination coin the machine will accept) without breaching any fare regulations.