4 digits number bike plates

I came a few times accross bikes having 4 digits number plates in London.
The plates are pretty small with a black background and the numbers are grey/metallic.
Anyone knows what these plates are? Maybe simply plates from another country? Just curious

Do you mean like this?They’re probably from Guernsey. From memory there are a couple of countries that use just 4 figures, but in Guernsey I am reliably informed you can still have black and silver number plates on a motorbike.



That’s right ! Just wondering how it works in reality.
Presumably you can only have 9999 bikes with this kind of plate.

Motorcycles and cars don’t share the same issue of number, so that you could have a 9999 on a car and 9999 on a bike. I assume, that like the cars have done, once they get to 9999, the nect number they will issue will be 10000. You can also apply to keep a number as personal issue such as a personalised plate over here. You also have to remember that Guernsey is not terribly big, about 60000 people live there.