The argument championed by the group against giving prisoners the right to vote focussed primarily on the idea that criminals had placed themselves outside of society by committing a crime. This too was one the main arguments of Locke's Two Treatises of Government. One of the main problems which faced Locke during Two Treatises was in trying to explain why society needed to punish people for crimes against property considering that the state of nature he had created was one of abundance with no need for people to worry unduly about that sort of crime. Locke argued that not only was committing a crime a crime against the individual target, but it was a crime against the whole of society because it represented a refusal of the law put in place by the wider population. In doing so, the criminal placed themselves outside of society because no rational person would disagree with the law - the criminal in this sense was reduced to nothing more than an animal, and it was the right of the wronged individual to punish this animal as he saw fit.
Man hath a Right to punish the Offender, and be Executioner of the Law of Nature.
The obvious failure of this argument is that is carries that any person who breaks the law, even for minor and arbitrary crimes, is seen as irrational and inhuman and should be punished accordingly. Taken to its logical extreme, 'Don't walk on the grass' means don't walk or be put to death, and Locke's abundant and pleasant state of nature which was so critical to his whole argument starts to fall apart.
The lesson that should be learnt in regards to prisoners is that whilst criminals should be punished, they should not be removed from society lest they be seen as less than human. Voting, which is defined under the Human Rights Act as a basic right of life, is therefore inherent in a person and cannot and should not be removed as a punishment for committing a crime. Criminals are to be punished in prison, not made into monsters, and voting is simply a part of ensuring that prisoners remain involved with British society and hopefully able to be integrated back into society after their term is served. It is also folly, as Lord Falconer seems to be suggesting, that some prisoners might get the vote, whilst others do not. Does this mean that some prisoners are not human?
Don't make the mistake of vilifying criminals any further than need be; they are to be punished but not stripped of their humanity - falling back to the solitary, poor, nasty, brutish and short state of nature of Hobbes is not what Locke had in mind, and it's not what I have in mind either.