‘We’re sailing out of the heads and turning left, then we’ll simply keep going until the ice cream melts,’ I explained, gesturing vaguely towards the Pacific. I’d been too plastered at the time of booking the tickets to take note of any exact geographical details.

Emerald’s work schedule and Amber’s helicopter parenting meant we were the last passengers to board and had only just made it to the departure gangway with moments to spare. Emerald had been delayed by a bereaved pet owner who’d insisted on hiring a medium to connect with her dead dog from beyond the grave, and Amber had run overtime with her tutor studying ‘fronted adverbials’ and ‘gerunds’, and how to calculate the kinetic energy of a two-tonne car travelling at thirty kilometres an hour. Apparently tutoring for kids is so common, Amber had decided that the only way to guarantee better grades for her precious progeny was to get tutored herself as well, enabling her to offer even more effective homework help.

I’d promised myself I’d level with my sisters about the cancer misdiagnosis the minute the boat set sail . . . but the moment was so perfect, with the tangerine sunset lighting up the sparkling harbour, which lapped like a contented cat on the sides of our ship, that I postponed my confession until after another round of cocktails. And then another.

I vowed to make a clean breast of things as soon as we found our cabin and were changing for dinner . . . But that didn’t go to plan either. Amber and Emerald had always pooh-poohed cruising; Emerald feared a cabin so small even a sardine would feel cramped, prompting Amber to fret that she’d have to ‘go outside to change her mind’. So, when my sisters saw our spacious, three-bedroom suite, complete with expansive balcony, they had to tilt their heads backwards so that their eyeballs wouldn’t fall out in amazement. They leapt about as though doing a Californian aerobics class.

‘You should get drunk and surf the net more often!’ Emerald exclaimed, dive-bombing onto her capacious bed.

‘Yes, let’s just keep our little sis in an alcoholic stupor!’ Amber agreed, popping open the ‘welcome aboard’ champagne that had been in an ice bucket, awaiting our arrival.

My sisters were agreeing. That was a first. How could I burst their bubble – their champagne bubble? My confession was on the tip of my tongue, but so was the Bollinger, which fizzed and frothed like the sea beneath our balcony.

I then pledged to come clean at dinner, but both my sisters were being so uncharacteristically attentive and kind – ‘May I buy you another drink? I’m thinking champagne – vintage’; ‘You take the best seat, Rubes, the view should be all yours – especially of the cute buns of the boys in the band’, and so on – that I didn’t want to break the fragile spell.