Following a strong introduction about the Feegle race - pictsies, and how to avoid them, our story begins among sleepy villages on chalky downs where a shepherdess once cussed the sky blue. Rob Anybody (a name, not an instruction) has been placed under a heavy geas (an obligation, not a bird). He must help a trainee witch confront a monster.

‘Witch’ is still a loaded term for some folk, so perhaps I should clarify. In the Ramtop Mountains, witches are midwives, vets and community nurses. They’re low on evil and strong on practicality. Yes, they inhabit the fringes of this world, and sometimes the next. That’s because they help bring the newborn into this life and will do what they can to make those leaving it comfortable. Magic? They prefer psychology. Occult imagery? The author sends it up. Discworld witches are another useful lens for the human condition.

Tiffany Aching, child hero, is apprenticed to the star of a travelling freak show. The kind where you pay good money to see the water otter and they show you a kettle. J.K.Rowling’s cloistered school for wizards contrasts with Pratchett’s open air school of practicality, cheap confidence tricks and a few hard knocks. People are respected for what they can do, not who they are. Here, Tiffany has presence like a pulsar; deceptively small, immensely heavy, and it all revolves around her.

Even in the poorest abode, the Disc’s witches get professional respect. “Would she like a cup of tea? I’ve cleaned our cup”. The great achievement of this writing is that these characters are three dimensional people with four dimensional minds.

Landscapes described in the series are recognisable as real places in England. The Uffington White Horse in Oxfordshire, standing stones and barrow mounds. Terry again: “I was born of the Chilterns and I live in chalk country, about two minutes from downland and lots of sheep; a lot of the hills around here have been in my mind’s eye when I was working on the books. There’s no shortage of ancient earthworks and mounds around here, but, alas, no white horses within walking distance”.

“Far too much downland has gone under the plough because of short-term agricultural policies. Mind you, I’m pleased to see that farmers are now being encouraged to turn downland arable back into turf. Sometimes they’re the sons of farmers who were paid turn the downland turf into arable!”

All good stuff then? Well… The only note which jars is this. When the central character is challenged and tested. Why does she need help? She’s the self-sufficient type who hardly requires rescuing, yet her familiars (the Nac Mac Feegle) must have their role. This echoes another novel (which Terry Pratchett advises people to read), Miss Masham’s Repose, by T.H.White. In this, a continuation of Gulliver’s Travels, a learned professor advises against patronising small folk just because of their size. Pratchett clearly won’t break White’s cardinal rule. Hence the Feegles have their quest, no matter how ‘bolted on’ it may seem. The witch has mentally grown up. The Feegles are unstoppable. The monster is outnumbered and doesn’t seem threatening enough. So the answer? Make the monster undefeatable! Oh, so how can she win? Thinking of course! So now it’s all logical, but it still jars.

Plying his craft in description and wordplay, there are parts that make you sad and parts that make you think. There’s always that daydream-popping line which makes you want to find someone and say “Hey, listen to this!” There’s another visit to the Lancre Witch Trials (an Olympic Games for party tricks), singing mice and perhaps the most fantastical of all Discworld images – ‘Dancing With Bees’.

Find out literally when not to use the word ‘literally’, why boredom is the rarest talent in the universe and why the worst thing you can say to a witch is “Do you want a balloon?” Learn another language too with the handy glossary. ‘Pished’ is apparently Nac Mac Feegle for ‘tired’. It’s fun to read, hard to criticise and clear about the bottom line. She might be called Tiffany, but no one’s throwing this little witch in the pond.