It’s not often that I see my dad avidly reading a children’s book. He usually prefers something with a bit more espionage, or physics. But I came home recently to find him leafing through my copy of J.B.S Haldane’s My Friend Mr Leakey. ‘He was a very well known scientist you know?’ he told me in that way that he does. ‘And a communist.’ I did know this. Haldane makes both of these things very clear in his unique addition to the cannon of great children’s books.

Haldane was an important scientific figure who introduced the world to gas masks, test tube babies and clones. His hunger for new and interesting ideas is vividly channelled in his children’s writing, the pages packed with fascinating facts. For example we learn that ‘an octopus has really got no legs. Those eight tentacles grow out of its head.’

There’s something fresh about his approach to magic too, as it says in the introduction. ‘He thinks a lot of the magicians in the old days were only doing, or trying to do what scientists or engineers do now, and that science can be a lot more exciting than magic ever was.’

What Haldane does is to present Mr Leakey’s magic in the most realistic and logical way possible, always thinking about how a spell would manifest itself if it could really happen. So when Haldane dons an invisibility hat we find out that unlike Harry Potter’s thrilling cloak the effects can be somewhat more confusing, ‘I felt my eyes shut but it made no difference. Of course now that I was invisible my eyelids and nose were quite transparent!’

We learn that magic carpets aren’t quite as precarious as they look, thanks to some useful charms that keep the air around it to keep moving with the carpet. The air is thoughtfully warmed and the lack of oxygen corrected by means of a potion, injected straight into the bony stump of a leg that has been magically screwed off.

We also get a useful insight into the daily life of the dragon. Not the ideal house pet it turns out, particularly when they have a cold. Pompey isn’t so much fire breathing, as consumed by the stuff, to the extent that he eats lava and requires a strip of asbestos (handy stuff) to travel aboard the flying carpet.

Dark magic presents itself in many forms. There is no Voldemort or Avada Kedavra curses here, but there is something much worse: ‘compound interest, one of the blackest sorts of magic.’ In between battling foul tempered genies and snaring robbers and stretching their noses, Leakey puts his anti-capitalist beliefs into action, turning up at the office of a money lender, scrubbing his debtors records and threatening to turn him into a sausage.

My Friend Mr Leakey has been illustrated twice, most recently by Quentin Blake (in 1972) and originally by Leonard Rosoman, who went on to become a wonderful fine artist. Both men suit the story perfectly, as Blake says in his introduction to the 2004 edition ‘this is like a play you can produce over again’. Blake brings his energy, wit and humour, Rosoman a slanted and enchanted view of the world.

When he appeared on Desert Island Discs, Rosoman summed up his way of looking at the world when asked to name his luxury item. He asked for a sloping lawn like the one from his holiday home. It wasn’t so much the lush grass that he wanted to keep, more the effect the slant had on the way people held themselves.

Haldane never wrote another book for children. The 1948 introduction explains that ‘he hasn’t felt like writing stories for children since about 1933, when Hitler got power in Germany, and the world became a nastier place. But he hopes the world will get nicer again now we have won the war.’

Seemingly it didn’t. But Haldane carried on his brilliant scientific career to the end, creating his own kind of magic. ‘On Monday I started doing sums about how to make new kinds of primroses and cats; for that is one of my jobs, and I think it is nearly as odd as Mr Leakey’s.’