One of the earliest chapters of the book is told from the perspective of Daenerys – also aged 13 – and involves a visceral description of her being fingered by Khal Drogo. I wouldn’t call it a sexual awakening as much as a rude one; frankly, I was horrified, though it didn’t stop me from devouring the rest of the series. For author Rachael Stewart, it was Mills & Boon that did it.

Her grandmother had shelves and shelves lined with the 15p paperbacks that she would eye up when staying over. At age 11, she snuck her first one down to read under the covers: “That was it, I devoured them so quickly, and I just fell in love with the whole world.” So much so in fact, she went on to write her own, and will publish her 30th title for Mills & Boon this year – though Stewart insists it was reading about love, not sex, that so enraptured her. Tropes, smut and happy endings: How Mills & Boon defined a genre Mills & Boon may be a publishing house, but it is better known as a genre: fast-paced plots, swept-away heroines and – of course – a good dose of smut.

The house has become a shorthand for a distinctive breed of erotica. It wasn’t always this way. Founded in 1908 by Gerald Rusgrove Mills and Charles Boon, the company started out as a general publisher (it even published the likes of PG Wodehouse), and didn’t pivot to women’s romance until the 1930s, when it capitalised on the popularity of tuppenny libraries to sell in high volume, cheaply.

They were distinctive for two reasons: their brown binding and their customer guarantee: a happy ending. Now in its 117th year, it’s an interesting time for the publishing house as it finds itself amid a newly revived fervour for romance. From Heated Rivalry to the Jilly Cooper renaissance, the appetite for romantic literature has reached feverish heights, with authors Sarah J Maas and Colleen Hoover ruling the book charts.

When I ask executive editor Flo Nicoll, who has overseen Mills & Boon’s output for the last 10 years, what she thinks of this development, it’s clear it is all old hat to her. “It’s funny watching people discover something that they think is shiny and new… we think of ourselves as the originals,” she says. As tropes like ‘sports romance’ and ‘enemies to lovers’ shape the market, Nicoll says it’s not really a concern for Mills & Boon: their back catalogue is so vast – now around 11,000 books – they have pretty much covered every fad going.

The romance formula It’s clear too, that the house doesn’t feel overly threatened by the influx of these new kids on the block, including those published by its parent company Harper Collins. Not only does the publisher have its own loyal fan base, but it plays to a different market than that being gobbled up by BookTok. Stocked primarily in supermarkets rather than bookshops, the average Mills & Boon reader tends to be a slightly older woman, based in a semi-urban or rural area and generally from a working class background.

But it’s clear that what has been the Mills & Boon bread and butter for so long has now bled out to a younger, more middle class readership. So what’s the secret? Nicoll insists there is no real formula, though Stewart, who churns out four Mills & Boon titles a year, is more forthcoming.

Their books look a little different to how they did in the 1930s – more diverse, less misogynistic, more explicit consent – but there is a basic method. “It’s like a recipe. First, you want to show the reader how good these people could be together before they even realise how good they are together.

Then you want to tear them apart.” This, Stewart explains, is called the ‘black moment’. “Then you want to bring them back together again, and have that joyous, uplifting moment at the end.” Throw it all together, and you’ve got a 150-200 page paperback ready to go. Stewart says each book takes her about two months to write, before a month of editing.

Is romance recession-proof? When I ask Stewart what it is that makes the novels so popular, she is unequivocal: the happy ending. “It’s like having a hug in the book.

You can read the whole thing and you know at the end of it you’re going to feel good, because you know it’s going to deliver on that deal.” Unlike other publishers, Mills & Boon publishes in distinct collections, whether that be their sexier ‘Dare’ or sweeter ‘Love Always’ line, which means readers can pick exactly what they want to read for any given mood. On the publisher’s website, these are categorised in groups as specific as ‘billionaire romances’ (currently very popular), ‘fake dating’, ‘medical’ and ‘marriage of conveniences’, allowing a choose-your-own-adventure style of reading. Mills & Boon, then, is a promise of both escapism and reassura