My son has barricaded himself inside. It’s my room he’s in – or rather the box room I use as my office – but it’s a Saturday and his cousin Nora is over, so it has been seconded for a greater purpose. The sight of them playing together so pleasantly is heartwarming. I should really say “the sound”, since I am ordered to stay downstairs while they ready the space for its intended use, and content myself instead with audibly supervising their clomping strides, a few clanking thuds, and a smattering of scattered laughter. He and Nora are seven, which means they’re both susceptible to loud bouts of miserable boredom, and any activities they can engage in without moping are to be welcomed. Even better, their spirited industry attracts the attention of my three-year-old daughter, who has soon departed the interminable game we’ve been playing with her Paw Patrol figurines, to clomp upstairs to join them.

After a while, my son comes down, sweaty and excited, demanding I cut some paper up for him. “Money shaped”, he says, presumably too animated to remember the word for banknote. I reach for the grown-up scissors with a pang of relief that he’s remembered he’s not allowed to use them by himself. It’s a good thing he has remembered this, because at this point, having had at least 15 minutes of completely uninterrupted peace downstairs while minding three children by myself, I would probably have given him a hand grenade if it offered me five minutes more. I cut the A4 page into 32 vaguely banknote-shaped strips, and he bounds off happier than if it had been real money.

Five minutes later, I am summoned upstairs to view the fruit of their labours. On the door hangs a sign which says “bookshop” above the additional legend “SPeshile 2 fore €15 – have fun and keep reeding!”. It’s a charming notice, not only for its game spelling, but also its delightfully specific notes of detail. One might quibble with the currency, but accept it on the grounds that both children have recently had trips to the Eurozone, and also the fact that the Euro symbol has always, let’s be honest, looked a little like a £ drawn by a child.

On the bed are laid out 32 of my son’s books, each with a little strip advertising their price. My presumption that he had not remembered the word for banknotes now seems erroneous, as the paper he had me cut was, in fact, for the pricing stickers resting loosely on the stock in front of me. Almost every single one says €6.50, so one might also quibble with the value inherent in that “2-fore-€15” deal he and Nora are advertising, but I digress.

On the door hangs a sign which says “bookshop” above the additional legend “SPeshile 2 fore €15 – have fun and keep reeding!”

I’m led immediately to the wares, with Nora acting as the saleswoman and my boy hanging at the back as a sort of hype man for the operation, pointing and shouting “books, books!” in the manner of a carnival barker. My daughter, meanwhile, is jumping avidly near the till, just happy to be included in this commercial operation, manically opening and closing a Fisher-Price cash register.

“Please sir, help yourself to our books,” says Nora, in a comically posh voice that is clearly not drawn from our shared experiences of book shopping in Walthamstow. She indicates a neatly tessellating row of my son’s favourites; several Dog Man books by Dav Pilkey; a half dozen of Jeff Kinney’s Wimpy Kid series; and the entire run of Bunny Versus Monkey, by Jamie Smart. The latter author is my son’s favourite, and one whose reputation has always preceded my own, since any time I’ve said that I, too, write books for a living, his immediate, and ubiquitous, reply has been “do you know Jamie Smart?”. When I tell him – yet again – that I do not, he reacts not just with disappointment, but disdain, as if this precludes me being a proper writer at all, relegating me to the status of someone who prints out political screeds to post on nearby street lamps.

“I’ll have two Bunny Versus Monkeys and a Dog Man, please,” I tell Nora, who dutifully removes their stickers and hands them to me. Through some form of fiscal alchemy, they have now become the bank notes I must hand to my daughter to put in the till and ring up my purchase. My son beams at the exchange, and I slowly realise their circular monetary policy has one major drawback; this shop is, effectively, an infinite space, and I must select every single book, one by one, and pay for it with the cash they’ve kindly provided.

For a solid 40 minutes, I buy everything they have in stock, and marvel that their facsimile of a perfect bookshop is one where all the books are free, while also featuring special offers, and the staff are posh, shouting, jumping, children. With their stock waning, and my pile of purchases now teetering on the desk beside the till, I take my memoir from the shelf and say, with smouldering pomposity, “I can sign it for you, if you like?”.

Delighted, they agree, and for the millionth time my son asks if I wrote that book which has my picture on its back. “Yes” I say, hoping that finally, within this temple of the written word he’s erected by my writing desk, my status as a real, proper author has broken through.

“Cool” he says. “Do you know Jamie Smart?”