IT’S a weird feeling: walking around in your own history. Some things were exactly the same. The bell for instance: loud and shrill. And the smell: polish on top of dust. And even some of the staff were the same: when he saw me, one of my old science teachers said loudly “I remember you!” although it turned out it was only because I was so bad at chemistry. And physics. And biology. And PE. Especially PE. They showed me an old report card from the gym teacher that read: “This is clearly not Mark’s favourite subject.” Like I said – walking around in your history: weird. I probably shouldn’t have done it.

Except that I’m glad I did – I’m glad I went back to my old school 25 years after leaving it because I was suddenly looking at something I thought I knew from a different angle. I have to admit it’s quite a long time ago now since I was at Robert Gordon’s College in Aberdeen – the 1980s – and at the time it was all-boys. It also still had some of the remnants of the post-war ethos. It was strict, quasi-military and intermittently violent. We had to salute the teachers. They wore gowns. They called us by our surnames. I was Smith, never Mark.

Fortunately, by the time I revisited the place in 2014, pretty much all of that had gone – Robert Gordon’s College is now co-educational and is much less formal than it was, although one thing certainly hasn’t changed: the principle on which the school is based. If you want to send your child here, it’ll cost you 14 grand a year for secondary and £8,765 to £11,905 for primary (excluding lunch) – the sort of money, obviously, that’s well out of the reach of most families.

Ah but, there are scholarships, aren’t there? Around five per cent of the pupils at Robert Gordon’s receive them and have their fees waived. It means the school and others like it can call themselves charities and save millions in tax – at least, they can for the time being. The Barclay Review into non-domestic rates recommended removing the eligibility of private schools for charity tax relief and legislation has now been introduced to implement the proposal. It’ll raise about £5million a year for the Scottish Government and private schools will have to find the money to pay for it.

How do I feel about this, as a former pupil of a private school? On the one hand, I’m suspicious about more tax-raising from a Scottish Government that’s developing something of a fetish for it. But on the other hand I understand what the author of the review, Ken Barclay, said this week about his proposals: “We looked at it on the basis of fairness and … I felt it was appropriate to level the playing field between the state sector and the private sector.”

I agree with Mr Barclay. Supporters of charitable status – including the headmaster of Robert Gordon’s College when I spoke to him during my visit – say schools such as theirs support families who cannot afford private education. This is a charitable act, they say. Therefore, they are a charity. But, at the risk being summoned to the headmaster’s office, I think that argument fails logically and morally. The logic has to be that similar institutions should be treated similarly, so why should state schools pay rates while private schools pay no rates at all?

Then there’s the moral dimension, which probably didn’t occur to me when I was sent to Robert Gordon’s in the 80s (cut me some slack: I was 11 years old) but it certainly struck me big-time when I went back to the school 25 years later. Time and again I was told the school was a charitable institution, but how can a place that charges many thousands of pounds for its services, and by definition excludes many people on average-to-low incomes, possibly be a charity? With apologies to my old English teacher who tried to teach me how to write an elegant sentence, it’s absolute b*******.

Obviously, the problems with private schools don’t end there – what about the lack of social diversity? – but I hope we can also see the positives, in particular how private schools can influence comprehensives. A headmaster of Castlemilk High in Glasgow once told me about the encouraging effect importing some of the more old-fashioned habits of the independent sector had had on his school: award ceremonies, assemblies and the like. I also remember a friend of mine telling me about how little the teachers at his state school, in one of the poorest areas of Scotland, expected of him as a pupil.

Can one sector learn from the other? Possibly, although there is always going to be a limit to how much schools that benefit from privilege can teach schools that are struggling with deprivation. But not all the success of the private sector is down to the social advantages of its pupils.

The headmaster at Castlemilk put it to me this way: the aim is to create an atmosphere of praise, encouragement and improvement and state schools can do that too. Private schools may be the ones with the charitable status, but we all know the truth don’t we? The real difference – the one that might actually justify the word charity – will always be done in the schools that are free.