Leading article: How to update a feudal institution

A political distraction was just what Gordon Brown needed once his grand ambitions for next week's G20 meeting in London began to look a little threadbare. Perhaps that is why he chose to engage with the radical idea of reforming the succession rules to allow royal daughters equal rights and to rescind the ban on marrying Catholics in his pre-summit trip to South America.

It will not have escaped the Prime Minister's attention either that such a reform would avoid any significant practical upheaval in the immediate term because the male succession to the throne – through Princes Charles and William – is already secured for a couple of generations.

Nevertheless, there is a strong case for scrapping male "primogeniture" in the royal succession, if only on the practical grounds that some of our most sensible monarchs, from Elizabeth I to our present queen, have been women.

The other reforms under consideration have merit too. Monarchy, by definition, is not "democratic". And so the idea of imposing modern principles of equality on what is essentially a feudal institution is a little absurd. Yet it does seem odd in our tolerant and diverse society to have a law stating that members of the Royal Family cannot marry Catholics.

The risk of a monarch subverting British freedoms to please the Pope (the great fear at the time of the 1701 Act of Settlement which imposed the restriction) would seem to be rather diminished these days. If there is to be a new spirit of religious tolerance in royal circles, however, it must extend beyond Catholicism.

There is no legal discrimination in the 1701 Act against the heir to the throne marrying a Hindu, a Muslim, or an atheist for that matter, because the likelihood of such a union was so remote three centuries ago. But there is considerable pressure on members of the Royal Family not to "marry out" culturally. This tacit discrimination should be repudiated in any new act.

We ought to use this as an opportunity for more fundamental constitutional reform. There is no longer any reason why the monarch has to be Protestant. Other lingering powers of royal prerogative – which are now exercised by ministers – ought to be dispensed with too.

And reform of the rules of royal succession should be an opportunity to disestablish the Church of England. Break the link between the Royal Family and anti-Catholicism and the case for privileging the Anglican Church in the constitution weakens considerably. Prince Charles has already professed his desire to be defender of all faiths.

There are associated benefits from such a change. Removing the right of bishops to sit in the House of Lords should lead to broader reform of the upper chamber and a strengthening of our democracy. Executed with conviction, Mr Brown's short-term political distraction could end up initiating a welcome new constitutional era.