Two years after taking up his post , Chief Rabbi Mirvis has been solid and dutiful. He has visited many communities throughout the UK with welcome warmth. Yet we are still waiting for his "big idea" to stir the masses and secure his legacy. Given that he is only a few years away from retirement, he has only a short time to make a difference.

His two greatest achievements in office so far were unoriginal. Visiting Limmud was reportedly a condition of his appointment (and, a decade overdue, no longer controversial in most corners of the community). The Chief Rabbi's very successful Shabbat UK was a South African import.

His latest proposal - to reform the barmitzvah ceremony - is unlikely to fill the void. As well as leyning, Chief Rabbi Mirvis want boys to learn to lead a prayer service. This skill should help them follow any service more easily, and ultimately take up the mantle of leadership. These are admirable aims, although the fact that so many barmitzvah boys apparently have trouble following a service indicates that something is going terribly wrong with our Jewish school system - much of it nominally run under the Chief Rabbi's "authority".

But the proposal has three disadvantages. First, it's hardly the ground-breaking idea we've been waiting for. Many barmitzvah boys already lead parts of the service in synagogues both to the left and the right of the United Synagogue.

Second, it could easily backfire on the US. Many United Synagogue barmitzvah boys already come from families that are virtually alienated from the synagogue, and who have very little interest in the ritual.

If leading the service is crucial for boys, why not girls too?

How many of them are going to be put off by this new - and from their point of view, onerous and unnecessary - requirement, and prefer to find other, easier places to mark their son's 13th birthday?

Third, while he is in danger of asking too much of some of the boys, he is apparently relegating the girls to "afterthought" status. He has announced he will hold a seminar on "developing and enhancing the way that we approach batmitzvah ceremonies". While that is welcome, it is disappointing that the girls' roles appear to be a secondary consideration.

Given the ferment and unhappiness of many women in the US and Orthodoxy, it would have been better had he announced an imaginative and concrete batmitzvah initiative at the same time as the barmitzvah plan, rather than saying it will come afterwards, assuming it will ever come at all. The attitude also begs the question of whether he will recognise that some 12-year-old girls - not to mention many grown-up women - would also like halachic opportunities to lead parts of the service.

To give him the benefit of the doubt, his proposal, when it comes, should for once be bold, and take into account these so-far unanswered aspirations.

Interested US families, for example, could be encouraged and helped to have batmitzvah ceremonies in women's prayer groups (which he has already endorsed), and with a Sefer Torah (which he has not yet).

After all, if leyning and leading services is so crucial to developing teenage boys' reading and Siddur skills - and is key to giving them a greater connection to the community, synagogue, and presumably God -why is it any less important for the girls?

Rabbi Mirvis's challenge, for both genders, will be to provide a parallel range of options that appeal to children with different levels of observance, knowledge and personalities. He could offer some boys the option of not leyning or davening at all (it is not a halachic requirement), but taking more experiential classes and presenting a dvar Torah in shul, as some of the girls do. Now that would be revolutionary.