This is the Traveline National Dataset (TNDS) which contains public transport timetables for bus , light rail, tram and ferry services in Great Britain. It does not include national rail or coach services.
The data is supplied in TransXChange format (XML).
To access the data you need to fill in the registration form, wait a couple of working days for Traveline to add you to the FTP server and send you a confirmation email. Your username & password will be your email address and the password you supply in the registration form.