What is a Show Plate?
What is the difference between a number plate and a show plate?
In short, a number plate is legal for road use whereas a show plate is technically not.
Typically, show plates are found attached to vehicles in car showrooms (hence the name "show plate") to catch the eyes of potential customers. A common use of a show plate in a showroom context is to advertise the make or model of the car it's attached to, for example, the registration "911" for a Porsche 911.
However, the term show plate has come to mean any number plate that doesn't meet legal UK road specifications. For example, when road users fiddle with fonts and character spacing to try and form a more aesthetically pleasing appearance for their plates (usually to create the illusion of words or names).
A less extreme example of a show plate, but still technically illegal for road use, is a plate without the mandatory manufacturer's name and postcode printed across the bottom line.
Show plates are sold as signs or novelty items and the customer attaches them to their vehicle at their own risk.