There’s nothing quite so burdensome as having a book to write. Maybe it’s not so bad when it’s your first book, but after that it’s a terrible chore. The publishing industry doesn’t help by paying authors up front. The temptation to pocket the advance and not deliver the manuscript is overwhelming. Believe me, when Douglas Adams said he liked the whooshing noise that deadlines make as they go by, he was speaking for all of us.

I signed up to write a book for Viking, part of the Penguin group, five years ago. Called Fully Comprehensive, it was going to be one part polemic about the shortcomings of Britain’s state schools and one part memoir about my misadventures at a series of sink comprehensives. I was due to hand it in in September 2010, but got sidetracked by the West London Free School, which became an all-consuming passion. At least, that was my justification for missing the first deadline.

My editor said she’d be prepared to overlook my tardiness if I knocked off a quick ebook for her and I ended up writing a 25,000-word essay called ‘How to Set Up a Free School’. Completely bonkers in retrospect because I didn’t get paid anything, but that’s what authors are like. Any excuse not to write the book, even if it means writing a completely different book.

To extend my deadline, I pitched my editor with another idea — a British version of Cultural Literacy. Cultural Literacy, for those that don’t know, was a 1980s bestseller by E.D. Hirsch that combined a searing critique of America’s public education system with 5,000 names, phrases, dates and concepts that every educated person ought to know. I proposed something similar, except I’d have Britain’s schools in my sights.

She agreed to the change and I made a pretty good start on it during the two months I spent in Kenya last year. But when I returned to London, I got bogged down in plans to open a second free school and, once that was out of the way, a third and then a fourth. Having spent so much time acquiring the skill set you need to open a free school, I couldn’t just discard it and go back to being a full-time author and journalist. The truth is, I enjoy managing a growing educational trust and the constant challenges it throws up. The new deadline went whooshing past and I was no closer to delivering the manuscript.

I had lunch with my editor towards the end of last year and told her I’d gone cold on the Cultural Literacy idea and come up with something else — a parents’ guide to what their children are learning in primary school and what they can do at home to help. I could see her eyes narrow — not again, Toby — but she reluctantly agreed on the proviso that I absolutely guaranteed I’d turn it in by the end of January. A new national curriculum is being introduced in September so she’d need the manuscript by January to publish it in time for that.

Needless to say, January came and went and I wrote not a word. I met my editor again at the beginning of February — this time, I’d been downgraded to a quick coffee — and told her there was just no point. I was never going to write the book. I might as well hand back the advance.

I thought she’d accept it gratefully, but I’d underestimated her. ‘You’re a fool,’ she said. ‘I’ve done some research and there’s no other book like this out there. I didn’t have very high hopes for any of your other ideas, but I thought this one might actually sell a few copies. You could have made some money.’

At that, something snapped. Goddammit, I thought, stop being pathetic. Just write the bloody thing. I phoned an old friend called Miranda Thomas — a physics teacher and the governor of a primary school — and asked her if she’d like to collaborate with me. She agreed and we’ve spent the past two months researching and writing like a couple of madmen. I think it’s the hardest I’ve ever worked in my life — harder, even, than on my Finals. But on Tuesday of this week we finally turned it in — all 120,000 words. Called What Every Parent Needs to Know: How to Help Your Child Get the Most out of Primary School, it’s due to be published on 28 August.