IT is sometimes easy to forget but members of the Scottish Parliament are sent to Holyrood wearing two hats.

One is the hat of a party politician, of course, and that is the one we see most often - in the debating chamber, in television studios, in local meetings or, increasingly, on social media such as Twitter. But MSPs have a second, parallel duty as parliamentarians.

Wearing that hat, they have a wider responsibility than mere party loyalty. They must represent all the people of their constituency or region, including those who did not vote for them.

They must also remember, irrespective of party, their most basic, most vital role at Holyrood: to pass effective legislation and hold Scottish Government ministers to account.

It is a subtle balancing act but some MSPs carry it off better than others. The SNP's Christine Grahame and Labour's Malcolm Chisholm are two such MSPs with a keen sense of their dual obligations. However, the distinction seems to be lost on some less experienced colleagues for whom parliament is solely a forum for advancing party interests.

The reform proposed today by Presiding Officer Tricia Marwick should give those MSPs a helping hand. Her call for committee conveners to be elected by parliament, rather than installed by their party leadership, is an attempt to rebalance the inner workings of Holyrood and encourage MSPs to recognise their twin roles.

An elected convener from a governing party would have a strong mandate to resist party pressure to block inquiries that were potentially embarrassing for ministers. Similarly, conveners from opposition parties might think twice before turning their committees into platforms to attack the Government.

The idea is borne of Ms Marwick's personal experience as a former member of Holyrood's governing corporate body, a role which is already decided by a vote among MSPs.

It would not be foolproof. Party politics will always exert the strongest pull on politicians, even among the least tribal. But by their election in the debating chamber, conveners would be reminded of their role as parliamentarians and they would acquire a powerful and independent new voice.

Holyrood's effectiveness has been called into question since the election of Scotland's first majority devolved government in 2011.

Ms Marwick says that is not the motivating factor, insisting the real test of any reform is that it improves parliament whether a majority, minority or coalition government holds power. Reforms should also endure, she believes, regardless of any future constitutional change. Her new proposal appears to fit that bill.

It is not a quick fix but part of a growing package of Holyrood reforms, driven by the Presiding Officer, that has already seen ministers summoned to parliament to answer topical questions and created a "super-committee" of conveners to quiz the First Minister on his annual programme for government.

The proposal for directly elected conveners should be widely welcomed.