Designs can be either registered or unregistered, the main advantage of a Registered Design over an Unregistered Design is that an Unregistered Design can only be used to prevent copying, whereas a Registered Design gives the Rights owner a monopoly and will apply even if the alleged infringer came up with the same (or similar) design independently.
The validity of a Registered Design can be questioned if:
The design is not new and original
The design features are functional
Customers are not concerned about the aesthetic features of the article when they buy it.
In the UK it takes roughly 3 to 9 months from the date of the initial application to the date of registration for a UK Registered Design.