Hi,
The Police are comming down increasingly heavily on number plate iregularities in the UK. This is being fueled by the introduction of automatic number plate recognition systems. If they can't read your plate they can't link a number to a database to establish if the bike (or other vehicle) is insured or stolen or whatever.
At the moment the offence carries a fine between £60 and £1,000 but it does not carry endorsement points. So you can't lose your licence because of it.
The Vehicle Excise and Registration Act 1994
http://www.hmso.gov.uk/acts/acts1994/Ukpga_19940022_en_1.htm section 42 says:
<quote>42.â€â€(1) If a registration mark is not fixed on a vehicle as required by virtue of section 23, the relevant person is guilty of an offence.
(2) A person guilty of an offence under subsection (1) is liable on summary conviction to a fine not exceeding level 3 on the standard scale.
(3) In subsection (1)"the relevant person" means the person driving the vehicle or, where it is not being driven, the person keeping it.</quote>
I believe that the most common event which may result in you being prosecuted for a number plate irregularity is if you are stopped for speeding. I don't think that the authorities are currently set up to force you to confess by post for a number plate offence in the way that they are with speed cameras.
Full rules regarding layout of number plates is here
http://www.legislation.hmso.gov.uk/si/si2001/20010561.htmBest wishes
Sid