There is actualy no test or certificate required to legaly drive a forklift, there is a recognised standard certificate of compitence which is overseen by a private firm.
What you will find is that some organisations have thier own internal training and certification standards and dont even consider the recognised 'certs' as acceptable (which is understandable).
Its all about compitency and your ability to demonstrate it plus, in the event of an accident, that you are able to prove that the compitency had been checked.
As an example, if you came to the heritage centre with a cert you would not be allowed to use any of the forklifts until you had completed out internal course and passed the required exam.
......and you can get to an approved level without a cert.
I know this is also true of some firms to!