When you think of the word "charity", what comes to mind?

People standing in the rain shaking a tin, perhaps, raising money for disadvantaged children, or aid workers slogging through 16-hour days trying to feed and house the starving thousands in refugee camps?

A private school situated behind high gates on a leafy estate, attended overwhelmingly by children from wealthy backgrounds, is probably not the first image that arises. Yet Barnardo's, Oxfam and private schools like Fettes College (fees per year: £22,170 for senior day pupils) are all charities; all, supposedly, so selfless and committed to good works and the benefit of society that they are rewarded with valuable tax breaks.

Now, call me a dangerous red and put me on an MI5 watch list, but it strikes me that there is something a little bit wrong about that. I'm no expert, but providing food and clean water to a family of eight that hasn't eaten in two days, or helping a child leaving the care system to set up home, seem to be quite different sorts of activities from giving a child with a place at the local comprehensive a degree of fees relief so they can attend the private school down the road instead, especially when such children make up perhaps only five or 10 per cent of that school's overall cohort. Somehow, I can't see Comic Relief rushing to make an appeals film about that.

There is no disability day centre at risk of closure, no food bank needing restocked, no race to find the cure for a horrible disease: just a group of privileged educational institutions that feel they deserve their tax breaks because they charge a small number of children lower fees and an even smaller number none.

So what sort of tax breaks are we talking about? Well, for one thing, as charities, private schools receive relief on non-domestic rates and you can easily see why they might want to hold on to it. The bill can easily amount to £200,000, but the schools receive 80 per cent relief. Meanwhile, state schools, including those in the most deprived areas of Scotland, are expected to pay the full bill or, rather, the local authority does on their behalf. So one school with children drawn mainly from the wealthiest sector of society pays minimal rates and one serving the poorest kids pays the lot. Is that fair? You make up your mind. But wait a minute, comes the counterattack, we private schools are so much more open and socially varied than we once were. Take the recent report by the Scottish Council of Independent Schools (SCIS). It highlights the fact that more than 400 pupils attending private schools in Scotland receive 100 per cent fees relief.

But 400 out of how many? Well, out of 31,146, according to the SCIS's last count. In other words, around 1.5 per cent of pupils. Funny how that sounds so much less impressive. Another, larger proportion receive means-tested bursaries, but the figures on exactly how many receive exactly how much, are harder to come by. What is evident is that Scotland's private schools remain inhabited largely by the children of the wealthy. That much has not changed.

It is now several years since the Office of the Scottish Charities Regulator (OSCR) warned private schools they had better make sure they were widening access to meet the minimum standard required to retain charitable status. Many passed, but a number of high profile institutions were found wanting and warned they needed to do more. They include Hutchesons' Grammar in Glasgow, Merchiston Castle in Edinburgh, St Leonards in St Andrews and Lomond School in Helensburgh. In January 2013, Fettes in Edinburgh was among three more schools to fail the "public benefit test" and, most recently, Loretto in East Lothian, where fees come in at £19,000 plus for senior day pupils, was told to improve its access arrangements or lose its charitable status. It is just as well the OSCR is policing the performance of the schools.

Better still, the charitable status of private schools should be abolished altogether, something that the EIS teaching union is to campaign for. If state schools, some of them serving large populations of children from deprived backgrounds, are losing out on these lucrative tax breaks, then private schools should certainly do without them.

Parents who wish to school their children privately would still be able to, but not subsidised by the cash-strapped state.