There are several arguments for having a written constitution, not least that the UK is the only country in the world not to have its constitution written and codified. With a written constitution everyone knows exactly what a government can and cannot do and would stop the government from becoming too powerful. An example of what this would stop would be if Tony Blair wanted to go to war he would have to go through parliament, whereas at the moment he can take the decision himself within his cabinet with no obligation to ask parliament.
It would also give the UK a chance to get rid of out-of-date parts of its constitution, such as the hereditary monarchy. However this would be very difficult to do as the Queen still has to sign all bills to make them Acts of parliament, and it is doubtful she would sign a bill that would abolish the monarchy.
All citizens of the UK would know their rights, they would be in a simple, easy to understand and codified format, just like in the US, instead of a part-written constitution which can be very hard to interpret. It would end the odd system where the underlying theories, such as the separation of powers, do not match up with the current practice.
However there are also arguments against changing our part-written for a written one. The first, and one of the most important arguments, is that the present system actually works well, as I quoted earlier, “If it ain’t broke, don’t fix it.” The present system is very flexible and it easy to make and repeal law, in contrast to the US where it is extremely difficult to get laws passed. And people like it so there is not a demand among the people for much change.
There would be no general agreement between anyone on what would replace the existing system, for example if the monarchy was abolished a lot would have to change, like money, many names (like the Royal Navy), there would be no more honours from the monarch and much more. And there would be a lot of dispute over how a President would be elected.
We would loose the great flexibility we have, we can change the rules very quickly if need be, like the enactment of the terrorism bill soon after the September 11th attacks in the US in 2001. The bill was written quickly and quickly signed by the Queen and turned into an act, all in the space of a week or so. In contrast other countries have a great deal of problems in changing their written constitution when need be.
Overall I think the UK should stick with what we have at the moment, a part-written constitution. It offers a great deal of flexibility, it works and there would be very little agreement on how a new system would work and what would replace all the institutions that bear a royal title and who’s rules and history revolve around the monarchy if it were abolished. Our current system also makes us unique in the world.