POLITICIANS, the argument goes, bring valuable experience and skills to their parliamentary work by taking on outside jobs. If that's the case, Scotland should have the best regulated farming industry in the world. Three MSPs augment their £58,678 salaries as farmers, the Conservatives Alex Fergusson, Jamie McGrigor and John Scott.

Mr Fergusson earns between £15,000 and £20,000 as a partner in a tenancy in Ayrshire. Mr McGrigor owns a sheep-farming business in Argyll. He earns between £3000 and £5000 for working one day a fortnight plus "seasonal work as necessary". Mr Scott is a partner in the family farm, also in Ayrshire, and earns £5000 to £10,000 working 14 hours per month.

These and lots of other nuggets are to be found in Holyrood's register of members' interests, which is published prominently on the parliament website. It makes interesting reading. I can't say I've ever noticed Mr McGrigor skipping committee meetings during the lambing season in the past but, thanks to this, I'll make sure keep an eye out over the next few weeks.

The Scots Tories' gentleman farmers belong to a minority of MSPs with second jobs but there are others.

Gil Paterson, an SNP MSP, is part-owner of Gil's Motor Factors, a family business in Bishopbriggs. He makes between £15,000 and £20,000 for less than 20 days work, putting him among Holyrood's top outside earners.

Other MSPs make a few bob from journalism. The SNP's Joan McAlpine earns £20,000 from a newspaper column. Alex Salmond has also been taken on a columnist since stepping down as First Minister, though we'll have to wait for the register to be updated before we can see if he is worth more than his colleague.

The register is more likely to tell you what jobs MSPs gave up shortly after being elected.

Paul Wheelhouse, the community safety minister, was sole director of an economic consultancy which he wound down after winning his seat. Labour's Mary Fee worked two days a week in Tesco. Like many MSPs she declared an income as a councillor until she stepped down at the last local election.

Hackles will be rising in some quarters, for sure. But they'll bristle worse at the news from Westminster, where outside work is much more common and earnings considerably higher. Gordon Brown, the former Prime Minister earned £533,000 over the past year, though it all went to his charitable foundation. Tory Geoffrey Cox, a barrister, made £452,000 and Respect's George Galloway £303,000 from media work. Earning six figures is rare but many MPs add tens of thousands to their £67,000 basic.

The comparison between Westminster and Holyrood has prompted some to suggest the former is one big rotten borough while the latter shines as a beacon of unimpeachable virtue. It's a rather complacent view and, tellingly, one that is not shared by Holyrood's Presiding Officer, Tricia Marwick.

Since former foreign secretaries Sir Malcolm Rifkind and Jack Straw were secretly filmed offering their services for cash to a bogus Hong Kong company, the debate about what is acceptable has sparked back to life. Labour and the Conservatives are at odds on the issue. Ed Miliband wants, specifically, consultancies and directorships to be banned. David Cameron fundamentally disagrees, telling the Commons on Wednesday that second jobs "enrich" parliament. At Holyrood, Jim Murphy has called for a ban on MSPs taking, specifically, consultancies and directorships and pledged to impose one if he wins next year's Scottish election. Unlike MPs, few MSPs hold such jobs. No MSP works as a paid consultant while the number of company directors is in single figures. That does not mean the Scottish Parliament should ignore the issue - and nor will it. Ms Marwick has asked the parliament's standards committee to consider the call and convener Stewart Stevenson will have it on the agenda in a fortnight's time. My guess is it will be hoofed into the long grass. MSPs may not want to reject it out of hand in case Labour win the General Election and make good their pledge to introduce a ban at Westminster, which would pile pressure on Holyrood to follow suit.

That might prove irresistible. The Scottish Parliament is rightly proud of having higher standards than "elsewhere," as Ms Marwick described, well, you know where this week. MSPs already face possible criminal charges if they fail to declare significant financial interests or engage in "paid advocacy," or lobbying, neither of which is an offence for MPs. It would be strange indeed if they gave themselves a freer rein to take a second job than their counterparts at Westminster.