Current UK registration plates consist of -
2 letters - region in the UK where vehicle was first registered
2 numbers - age identifier
3 letters - random
The age identifier changes twice a year - 1st March and 1st September.
A random example using the 56 age identifier
Car was registered in Edinburgh(SM)between 1st September 2006 and 28th February 2007(56). The last 3 letters are completely random.
To use the above plate to show the newest registration in use right now -
(registered in Edinburgh between 1st September 2010 and 28th February 2011).
On 1st March 2011 the above plate would read -
Then on 1st September 2011 it would be -
The current system will last up till 2050, but will need to change from March 2051. Assuming we are all still here that is.