The taste of bile fills my mouth and there are tears in my eyes as, blindly, I stumble back to the room where the party is in full swing. I catch sight of Jude grinning like a loon and dancing to ‘Hot, Hot, Hot’with his arms round his babe of a wife. He glances up and, for a moment, I think he catches my eye as a stricken look flits across his face. Then it’s gone and I duck out of sight.

When the Hawaiian-shirted barman moves out of the way, I slip behind the beach hut and swipe two unopened bottles of Totally Tropical out of a cardboard box. I double-check that it’s the alcoholic version. There have been enough mistakes tonight and that’s one that I really don’t want to make. Back on my way to Lauren I pass the kitchen, so pop in to liberate a tray of canapés.

I find her still in the loo, looking dazed and confused and not a little drunk.

‘Come on,’ I say, grabbing her by the arm. ‘Let’s get out of here.’

‘But you’re working,’ she says.

‘Not now.’ I stop and sigh. ‘I just saw Blake Chadwick snogging one of my younger, more beautiful colleagues. He can stuff his job up his bottom.’

‘All men are bastards,’ Lauren declares.

‘Yes,’ I agree. ‘They are. So let’s go and get stupidly drunk on this rubbish.’

Out on deck, and the cool breeze hits us like a slap in the face. We head towards the stern, where I see a ladder going up to another level. We’d be well out of anyone’s way if we can get up there. No one would ever find us. With much huffing, puffing, pulling and pushing, Lauren and I climb it.

As I suspected, there’s no one else up here. No one else foolhardy enough.

It’s some sort of flat roof with rails along the side, but other than that it’s blissfully empty. We can still hear the steel band playing its heart out on the deck below. The inky black waters of the Thames are far beneath us. I help Lauren to sit down, then she reciprocates. Our costumes are ridiculously uncomfortable but I quickly realise that if we were to take them off then we’d succumb to hypothermia within minutes. It may be summer, but out here on the river in the night air, it’s not overly warm.

I undo Lauren’s pineapple leaf hat and she does mine. I feel like throwing them into the Thames, but sense prevails and I put them down next to us so that someone else in the future can be humiliated by dressing as a tropical fruit.

‘I’m never going to eat pineapple again,’ my sister says.

‘Me neither.’