‘Oh, god. You haven’t gone and actually got cancer, have you?’ a tipsy Emerald joked.

‘Well, now, that really would be funny,’ my mother said, a smile acid-etched onto her face. All she needed was a black chariot drawn by howling, multi-headed hellhounds to complete her ‘Dark Mistress of Torment’ image.

A fierce desire to shock my merciless mother down to her very hair follicles came over me in a rush. ‘I’m just feeling a little bit nauseous, you know, because of the baby.’

All three heads jerked in my direction like a small school of hooked herring.

‘What baby?’ Emerald, who’d been up since dawn trying to arm-wrestle a naked turkey into the gynaecological position in order to stuff chestnuts up its orifice, had developed the demeanour, aching legs and mood swings of a member of a long-haul cabin crew. There was no point messing with her.

‘The baby I’m carrying. I wasn’t going to say anything till the three month mark, or until after the termination,’ I added, to shock my staunchly Catholic mother even more, ‘but—’

‘What?’ Amber said, similarly flabbergasted. ‘How can that be? At your age?’

‘No, it can happen,’ Emerald espoused. ‘The famous change-of-life baby.’ Fuelled by champagne, my oldest sister ploughed on without thinking. ‘Especially, biologically speaking, if the vagina hasn’t had time to become hostile. Vaginas love new sperm. With a new lover the vag hasn’t had time to build up immunity. It’s a very, very warm and welcoming place indeed.’

‘New lover? What the hell does that mean?’

We three sisters were sitting facing the swimming pool – our backs to the path that ran down the garden to the barbecue below. Only Ruth, with the pool behind her, had noticed Harry’s reappearance, but had chosen to say nothing. She just sat there, gimlet-eyed, in full Madame Defarge mode, with her imaginary guillotine and invisible knitting. We swivelled in unison to face him.

Emerald’s words hung, irretrievable, in the air. For a moment, all that could be heard was the splash and splosh of the cousins frolicking down the deep end, and the cackle of the kookaburras, who were clearly in on the joke.

‘What do you mean, “new sperm”?’ Harry asked again, aiming his barbecue tongs at Emerald like a weapon.

As elephants in rooms go, this one was more like a woolly mammoth. Emerald and Amber’s eyes jumped to mine. I just kept smiling until my face cramped and my teeth felt like they would fall out. Remorse racked my whole body. I figured now would be a good time to fake a terminal illness – say, necrotising fasciitis – or possibly to emigrate to New Zealand.

‘Tell me!’ Harry demanded. ‘What the bloody hell’s going on?’