"Well, I was thinking of just popping down to Viva Mexico…" I said (and almost added "as usual'), looking plaintively at Yvonne's bright red lips.

"Na," William said, grimacing. "I fancy some oysters. Let's go to the Cafe Royal, what d'you say?"

I said, "Umm…" I thought, Oysters…

"Our treat," Yvonne said, taking her husband's arm and smiling.

I met Yvonne and William at university, back in the cusp of these times, our years at Stirling neatly bracketing Thatcher's first and second victories.

They were doing business-studies courses. He was from Birmingham, though his parents were Scottish. She was from Bearsden, outside Glasgow. They met in the first week and were an item when I bumped into them in the sports pavilion a term later, one Saturday afternoon when William was about to play rugby and Yvonne was looking for a squash partner. I'd been waiting for my opponent — a guy from my media-studies course — to show for half an hour and was about to give up and head for the bar when Yvonne suggested we played each other. She thrashed me. We must have played a couple of hundred games over the years since then and I've beaten her exactly seven times, usually when she's been about to go down with — or is just recovering from — a cold or some other ailment. I blame the drugs, and the fact that, apart from the occasional athletic sex session with Yvonne, a fortnightly game of squash is about the only exercise I get.

Yvonne and I were just pals until she and William moved to Edinburgh three years ago and one time when William was away she and I met to go and see — of all things — Dangerous Liaisons, but never made it to the film because we just got drunk in the pub instead and somehow started kissing, and then in the taxi on the way back to Cheyne Street had to be told to cool it by the driver because we were practically fucking on the back seat. We got half a metre inside the front door of the flat then it was knickers down, trousers down, and a knee trembler against the wall, her head forced forward by the gas meter and my backside getting cold from the draught coming in through the letter-box.

We usually make it to the bed these days but it's been an interesting and varied physical relationship and Yvonne swears she does things with me she'd never even mention to William, whose predilections seem to begin and end with quite liking his wife to wear a basque and stockings. Considering he looks like such a broth of a boy it's slightly disappointing to be told he's squeamish about blow jobs and quite horrified — however politely and apologetically — at the idea of going down on Yvonne. So that, plus wrestling covered in baby oil, eating ice-cream from her vulva, pretend rape and bondage sodomy are all treats reserved for me, apparently.

So we're sitting in the Cafe Royal after a breezy walk down North Bridge and William has slipped a dozen live oysters down his throat (Yvonne and I had chowder) and we're talking computers because I use them and I'm interested in them and William works for a company that makes them; their Scottish manufacturing base is in South Queensferry but the company's HQ is in Maryland in the States. He was due to fly out there today but just as he was about to kiss the lovely Yvonne goodbye this morning and leave their delightful, triple-garaged, split-level lounged, sauna'd, jacuzzi'd executive villa with ensuite facilities and satellite dish set in an exclusive walled prestige development amongst mature trees with a residents-only country clubhouse, restaurant, pool, Nautilus gym, squash and tennis courts, he got a phone call telling him the trip had been postponed for a few days.

We're sitting at a table in a corner of the restaurant; William and Yvonne sit side-by-side on a green leather bench seat opposite and I'm on an ordinary chair, directly across from Yvonne. She's playing footsie with me under the table, her shoe off, her black nylon foot stroking my right calf. I'm assuming the starched white tablecloth is long enough to hide this.

Meanwhile I'm talking about 486s and clock-doublers and the up-coming P5 chip and CD-ROM and there are at least three things going on in my head because part of my brain's busy handling my conversation with William, another part is revelling in the sensations being produced by his wife's foot sliding up to my knee, giving me a monstrous erection under my napkin, and a third part is sort of sitting back listening to me talk to this cheery, affable man I'm cuckolding and it's thinking what a cool bastard I am, and how chatty, informed and charming I'm being while suffering this delicious, hidden, public, prick-engorging distraction. We're talking about multi-tasking and I almost want to say to him, "You want to know about multi-tasking? I'm doing it right now, pal."

Yvonne is looking just a little bored with all this computer talk, which is probably why she started fondling my leg in the first place. She's not into computers; she's into bankruptcy management. Straight from university she joined a small firm specialising in easing the death throes of failing businesses. She's been all over Britain doing this stuff and last year they made her a director. It's not a small firm any more. Growth industry.

She delicately stifles a yawn and sits back in her seat, and I take a sudden breath which I have to disguise with a cough as her foot suddenly slides up between my legs. I foolishly lift my napkin to dab my lips after the pretend cough, and Christ, there's her foot resting on the front of my seat, her stockinged toes flexing forward to stroke my cock through the material of my trousers. I put my napkin down again quickly and return to the subject of full-motion video from CD-ROM, hoping nobody saw her foot. I don't think so. Could have been embarrassing if there'd been a waiter nearby. I surreptitiously pull the tablecloth over my lap and her foot as well. She's sitting back in her seat grinning slightly at me, toes curling and uncurling as they stroke me.

I lift my champagne flute, nodding wisely at something William has just said.

"Anyway, must dash for a slash," he says, rising. Yvonne's foot tenses against my crotch, but she doesn't take it away.

Yvonne and I watch him go then we lean over the table towards each other at the same time.

"God, you look fuckable," I tell her.

"Mm-hmm," she says. She shrugs. "Sorry about all this."

"Never mind. God, you look fuckable."

"Want to meet up the day he goes?"

"Yes," I gulp. "Yes yes yes."

"Take off your shoe and get your foot up between my legs," she says quietly. "I'm not wearing any knickers."

"Oh, Christ."

An hour later and I'm standing in the gents toilet back at the paper with my right sock wrapped round my dick, masturbating. The smell of the sock clings to the skin around my nose; before I wrapped it round my cock I sat sniffing it, hauling its scent deep into my lungs. This is the second wank I've had; I really was about to come as I sat there eating my lobster with Yvonne's foot stroking my crotch and my foot up her skirt. I had to excuse myself, withdraw my foot, get my shoe back on and walk awkwardly down to the gents in the Cafe Royal to pull myself off before I disgraced myself at the table. Barely had to touch the thing. This is taking only a little longer. The sock reeks with a fiercely erotic woman-scent. Thank God we were eating seafood. Yvonne… Ah, here we go…

"Cameron. You all right?"

"Fine, Frank."

"You look a bit pale."

"Feel all right."

"Good. Carse of Gowrie."

"Pardon?"

"Carse of Gowrie. You know; near Perth. Guess what the spell-check prefers?"

"I give in."

""Curse of Gorily"!"

"Stop it, you'll make me cry."