There were other weird and wonderful things happening, too. By the second week of our cruise, Amber had packed away all her make-up and chic summer capsule wardrobe in du jour shades and taken to slobbing about in Emerald’s board shorts and Birkenstocks. By week three she’d stopped shaving her armpits and brushing her hair. Catching a glimpse of her one morning, I thought it might be time to schedule an audition for her in a reboot of The Witches of Eastwick.

‘I’ve discovered my middle-age superpower: I’m invisible! The cloak of invisibility is upon me. And it’s so fucking liberating,’ she exclaimed.

She’d also started to swear with relish, and her shoulders now shook when she laughed. And when Amber laughed hysterically, it wasn’t long before she started snorting in the most deliciously unladylike manner. Our mother would have been horrified.

Emerald, on the other hand, who was known for looking as though she’d dressed in the dark choosing items from a charity bin, had started sashaying around the ship in her designer clobber with the kind of walk that should always be accompanied by the brass section of a big band. She’d restyled her hair, too, dropped a few kilos and looked ready to run a marathon – or she would be if her feet were not clad in dainty, bejewelled slingbacks. Emerald had always berated Amber and me for torturing our poor tootsies in high-heels – she said it was akin to Chinese foot binding and other archaic cruelties – but now she clackity-clacked in vertiginous stilettos everywhere she went.

‘Well, I have been getting a lot of exercise,’ Emerald explained, flicking the loose elastic of her shorts as we took up our sunbathing spots on the pool deck. ‘Not from bloody gym sessions or dieting, ugh,’ she said, grimacing, ‘but from toy-boy dodging. Hiding from a cub you’ve shagged involves a lot of ducking and diving, which is incredibly aerobic.’

I knew what she meant. That very morning, on the way to meet Brody, I’d glimpsed Wayve on the lido deck and immediately dropped to the ground and crawled out of sight, keeping my head down as if I were dodging enemy fire.

‘Oh, god, don’t look up. Here comes one now,’ Emerald gasped.

I paused in my application of sunscreen to scan the row of board-shorted cavaliers barrelling our way. ‘Which one?’

‘The bloke I kicked out the other night, remember? I could put up with the tattoo on his bicep that read Death Before Dishouner – spelt D-I-S-H-O-U-N-E-R, I kid you not – but not the tat on his chest, which read Never Don’t Give Up.’ She lifted her open book to an inch below her eyes, watching his approach like a detective on a stakeout.

‘Oh, yes.’ I cringed, laughing. ‘That’s definitely a grammatical faux pas too far.’