"I mean like in psalm whatsit," I explained.
"Right," he said. There was a familiar teasing look in his eye. "Do you think you might be thinking of the Lions of Longleat?"
Rebecca suddenly leaped to her feet. "I'm going to jump off the bridge!"
She looked round beaming expectantly. Everyone else was in shorts or little dresses, but she was naked except for a tiny sliver of Calvin Klein brown nylon.
"Why?" said Mark.
"Because attention was diverted from her for five minutes," breathed Sharon.
"We used to do it when we were little! It's heaven!"
"But the water's very low," said Mark.
It was true, there was a foot and a half of baked earth all the way round the water line.
"No, no. I'm good at this, I'm very brave."
"I really don't think you should, Rebecca," said Jude.
"I have made up my mind. I am resolute!" she twinkled archly, slipped on a pair of Prada mules, and sashayed off towards the bridge. Happily, there was a bit of mud and grass attached to her upper right-hand buttock, which greatly added to the effect. As we watched, she took off the mules, held them in her hand and climbed on to the edge of the parapet.
Mark had got to his feet, looking worriedly at the water and up at the bridge.
"Rebecca!" he said. "I really don't think ..."
"It's all right, I trust my own judgement," she said playfully, tossing her hair. Then she looked upwards, raised her arms, paused dramatically and jumped.
Everyone stared as she hit the water. The moment came when she should have reappeared. She didn't. Mark started towards the lake just as she broke the surface screaming.
He ploughed off towards her as did the other two boys. I reached in my bag for my mobile.
They pulled her to the shallows and eventually, after much writhing and crying, Rebecca came limping to shore, supported between Mark and Nigel. it was clear that nothing too terrible could have happened.
I got up and handed her my towel. "Shall I dial 999?" I said as a sort of joke.
"Yes ... yes."
Everyone gathered round staring at the injured hostess's foot. She could move her toes, daintily and professionally painted in Rouge Noir, so that was a blessing.
In the end I got the number of her doctor, took the out-of-surgery hours number from the answerphone, dialled it and handed the phone to Rebecca.
She spoke at length to the doctor, moving her foot according to his instructions and making a great range of noises, but in the end it was agreed there was no breakage, not really a sprain, just a slight jar.
"Where's Benwick?" said Nigel, as he dried himself and helped himself to a big slug of chilled white wine.
"Yes, where is Giles?" said Louise Barton-Foster. "I haven't seen him all morning."
"I'll go and see," I said, grateful to get away from the hellish sight of Mark rubbing Rebecca's delicate ankle.
It was nice to get into the cool of the entrance hall with its sweeping staircase. There was a line of statues on marble plinths, oriental rugs on the flagstone floor, and another of the giant garish crests above the door. I stood for a moment, relishing the peace. "Giles?" I said and my voice echoed round and round. "Giles?"
There was no reply. I had no idea where his room was, so set off up the magnificent staircase.
"Giles!" I peeked into one of the rooms and saw a gigantic carved-oak four-poster bed. The whole room was red and it looked out over the scene with the lake. The red dress Rebecca had been wearing at dinner was hanging over the mirror. I looked at the bed and felt as though I had been punched in the stomach. The Newcastle United boxer shorts I bought Mark for Valentine's Day were neatly folded on the bedspread.
I shot out of the room and stood with my back to the door, breathing unsteadily. Then I heard a moan.