[dyno12345]

http://en.wikipedia.org/wiki/Pardon#United_Kingdom

Pardons are extraordinarily rare in the UK and normally only granted for misapplication of the law

[thejsjunky]

The article seems to say the opposite:

'It is the standard policy of the Government to only grant pardons to those who are considered "morally" innocent of the offence, as opposed to those who may have been wrongly convicted by a misapplication of the law.'

It also mentions that in 1996 there was a pardon given as a "reward for information".

[dyno12345]

It seems to say both that it is and it isn't at different points