In his article on the implications of Scottish devolution, Vernon Bogdanor calls for a UK-wide constitutional convention, possibly leading to a written constitution (A one-state solution to the English question, 26 March). Using the analogy of a tennis club, he argues that the absence of a codified constitution alienates citizens from the state: "If you have to ask" for clarification of unwritten, often obscure rules, then "you don't really belong".

As someone who has never been content to live in a country where the rules are hidden and imprecise, I cannot disagree. But Bogdanor neglects a more important principle: whose rules are they, and for what purpose are they instituted? It is here that his constitutionalism ignores the claim of popular sovereignty: the people's right not only to know the rules, but to make them.

The core of the constitutionalist case – from the Levellers' Agreement of the People of 1647 to the Scottish Claim of Right of 1989 – is that the people, not parliament, have the final word. There should be fundamental rules, covering the principles and institutions of government and the rights of citizens, that "we the people" make, and by which elected representatives are bound.

If a democratic constitution embracing popular sovereignty were realistically on offer in the UK, Bogdanor's call for the left to "take the lead" in calling for it would be welcome. Such a constitution would not only repudiate the unprincipled "muddling through" that has traditionally characterised the British government, but also overturn the two pillars on which its opaque and oligarchical powers rest: the crown prerogatives and the sovereignty of parliament.

However, no such constitution is on offer, nor is it likely to emerge from a UK constitutional convention. Westminster and Whitehall won't suddenly embrace a constitution on democratic grounds. Rather, they are motivated by a desperate desire to hold the UK together.

That's why the House of Commons political and constitutional reform committee, in a report echoing Bogdanor's call for a UK-wide convention, recommends that its terms of reference be limited to territorial devolution, and not wider questions of democracy. The main problem, as they see it, is the risk that Scots might vote for independence, thereby ending the pretentions of the British dynastic state forever.

This is doomed to fail. The British establishment has never understood Scotland's distinct constitutional grievances. These stem from a different constitutional tradition, in which the state was weaker and society stronger.

In the referendum, Bogdanor writes, "Scots will decide whether they want to remain British." This is untrue. Most Scots identify as British and Scottish, and the referendum is not a choice between these identities. Just as an independent Norway is still Scandinavian, so an independent Scotland will still, in a cultural and geographical sense, be British.

What is at stake is not identity, but democracy, embedded in the principle of popular rather than parliamentary sovereignty. While Westminster offers only a territorial compromise (combined with an unreformed electoral system and House of Lords, crown prerogatives, and repeal of the Human Rights Act), the Scottish government is offering a real constitution, produced inclusively, that will establish an independent democracy fit for the 21st century.