If you were scouting ideal locations to build a prestigious preparatory school for girls, how high up the list would you put a windowless, concrete underground car park built in 1973?

If you were on the Board of Governors of the City of London School for Girls, you would apparently put it first on the list.

In January, the City’s top-ten independent girl’s school (annual fee: £17,000) announced that its preferred location for its new prep school is the car park beneath Thomas More House, one of the love-them-or-hate-them brutalist blocks of the Grade II listed Barbican Estate. (Full disclosure: I live there, and I love them.) The current school is located in purpose-built premises in the middle of the estate.

It would honestly be difficult to come up with a worse location to educate girls aged 7-11. The car park is underground. It receives very little natural light. It suffers from water ingress (several of the parking spaces are unusable for this reason).

It has no ventilation. It has one narrow access road, and is located off a busy street with no space for parents in large luxury off-road vehicles to drop off their children. And like much of the Barbican, it’s riddled with asbestos.

It’s hard to see how the school fits the government’s own standards – “Good quality daylight within the learning environment is essential,” says the Education Funding Agency. Perhaps this is an advantage of being an independent school. You are free to deprive children of daylight for six hours a day in return for £17,000.

Not only does the car park have these problems, but the school has far better options close by: the virtually-unused Barbican Exhibition Halls, and, even better, the London College of Fashion’s Golden Lane building, soon to be vacated and just over a quarter of a mile away.

So how on earth can these plans even have progressed beyond a governor’s fever dream, and become a genuine possibility? The answer lies in the arcane, medieval and baffling governance structures of the City.

Shortly after I was elected last year, one long-standing member described the City of London Corporation to me as, “One third local authority, one third lobbyist for financial services, one third historical re-enactment society.”

This was brought home to me when I was fitted for my robe. Yes, I have a robe. It has fur cuffs.

The City’s unique status as the oldest democratic body in the UK has created lots of quirks in its status, and they lead to bizarre situations like this. The school plan looks at first glance like a London borough gifting enormously valuable central London real estate to a private school.

But, the City of London argues, we’re not a borough. And legally, it’s right. The Municipal Corporations Act of 1835 gave the City special dispensation to ignore the overhaul of how London was governed – and there are all kinds of subsequent local government legislation that doesn’t apply there.

All the same, the City receives council taxes, maintains roads, collects rubbish, decides planning applications, runs libraries, and licenses restaurants and bars, just like any London borough does. In simple terms, it quacks like a duck. No other local authority could get away with gifting publically-owned land to a private school. The City should not either, regardless of the smoke and mirrors it might use.

The other big problem here is that the City is on both sides of the negotiating table. The City of London, a local authority that owns the freehold of the entire Barbican, intends to gift the car park to the City of London, the administrator of a private school).

This conflict of interest arises pretty frequently, such as when the City of London has to decide planning applications made by… the City of London. It may not surprise you to learn that the City approved 99 per cent of planning applications in the 12 months to September 2017.

The ‘school in a car park’ plan is a perfect example of why local authority reform has happened over the last 200 years. Because if you don’t improve the systems, mad things happen. Until serious reform takes place, the Square Mile will remain more prone to mad things than most local authorities.

Richard Crossan is a Labour member of the City of London’s Court of Common Council, representing the ward of Aldersgate.