Reforms to the Scottish Parliament's committee system are much needed.

Holyrood's committees were seen as a great success in the early years of devolution. Indeed in many ways they have been. They have brought government much closer to the people of Scotland, giving experts and ordinary people from all sorts of backgrounds - science, business, health, communities and charities among them - the chance to speak directly to those in power.

This is immensely valuable for both sides, and when it works it should ensure that better laws are passed, having been scrutinised by better-informed politicians.

But there have been significant problems in recent years. Labour's Hugh Henry identified a "cult" of obedience and slavishness in his coruscating attack on the Public Audit Committee in May.

The SNP-dominated committee had held back on criticising the Scottish Government, he claimed, forcing a minority report to be issued. Similar concerns have been expressed about other committees, which have been accused of refusing to call witnesses hostile to government policy, or acting to shield ministers from criticism.

The proposals from presiding officer Tricia Marwick for reform of the system are therefore very timely.

It may be, as Ms Marwick insists, that her proposals are not a direct response to the growing concern over politicisation of committees.

But there is evidence of a failure of MSPs to understand their duty as committee members to scrutinise proposals and impartially hold the government of the day to account.

It is essentially a lack of maturity. This is a young legislature still. Westminster, with all its history, has built up a strong tradition of robust and effective committees, whose members pride themselves on the job of committee work, and keeping it at a remove from party affiliation.

Scotland's parliament and its parliamentarians have not yet established the same tradition. But without a second chamber to fall back on, Holyrood arguably needs robust committees far more than the House of Commons. Electing conveners by secret ballot could go a long way to ensuring those chosen are the independently-minded MSPs seen to understand this concept and who have the clout to defend their committees.

A mandate from the Scottish Parliament would emphasise they have a responsibility to that parliament as well as their party, and the dual role they need to play. MSPs must realise that it is in nobody's interests to allow the Holyrood committee system to become politicised through slavish party tribalism.

Ms Marwick's proposals are not foolproof. If a party has a large majority it is hard to see how its members could be prevented from electing pliant conveners, or how such conveners could be held to account once chosen. But it would make this a much less likely scenario.

These changes are vital if the committee system is to justify its reputation as the Scottish Parliament's "jewel in the crown".