A written constitution?

I've just seen BBC News: Straw's written constitution hint with the suggestion that the UK could get a written constitution produced over the next ten to twenty years and it's got me thinking.

I used to dismiss the idea in the belief that the UK's system worked perfectly well without one, and indeed allowed greater scope for flexibility. But nowadays I'm not so sure. The changes of the last eleven years, particularly devolution, are taking time to settle in and there are still some major areas not properly addressed (such as the West Lothian Question).

A written constitution that could only be changed by referendum could well have required proponents of devolution to sort out the English question before submitting the scheme to the people and there be democratic legitimacy for whatever situation was created. A written constitution would also remove the ability of parties to demand voting system changes as part of a blackmail in a hung parliament, which makes me wonder why the Liberal Democrats are so keen (although they've also never cottoned onto the fact that proportional representation would also require them to actually make a choice between the main parties and tell the public in advance of polling day).

Of course this relies on such a constitution being particularly well drafted. But are other countries that have constitutions really so badly governed because of them? Where have they had conflict that the constitution has made resolution hard? Many of them could have arisen without one.

This is an idea that warrants much further discussion...