As I rounded the corner by the school, a small dog yapped at me, straining at a leash held by someone I couldn't see. A few steps later I realised it was the big woman from the street next to mine. The dog continued to pull and jump and make its barky noises, the sort of thing that frightens children and adults who don't understand and see it as aggression. In fact it's usually just an inquisitive, talkative young canine that means no harm. The woman pulled him back sharply.

She was in her late thirties, I would guess. When I say she was big, I mean tall - at least six feet - and possessed of a physique that in a man would be called well-built. She wouldn't have looked out of place on a rugby pitch. Not fat, nor muscular, but... imposing is a word that might do the job. And there is nothing wrong with that in my opinion, but such physical specimens are probably teased in their school days. Not bullied, because they are more than big enough to look after themselves, but I'll bet this woman had had nicknames behind her back, referring to her size. Even as she entered the adult world, most men would have been put off by her dimensions, fearing she would have been too much for them. So, she might have found a niche as an amateur dominatrix, which wouldn't necessarily lead to long-term personal relationships and domestic bliss. She might by then have gone down the lesbian route, possessing the bulk and power of a man without the innate male characteristics that turn the sapphic sisters off.

All of this flashed through my mind in a few seconds because I had thought it before. She was fairly good-looking but not exactly pretty. The world is full of such women - and men, come to that. We are unhappy with our imperfections and try to gain confidence from the fact that we're not hideous. We're acceptable. The ugly old male assessment, "I wouldn't kick her out of bed" is just a grotesque way of saying a girl was perfectly acceptable, and the boys who used the expression were merely trying to give themselves a bit of kudos with their friends, whether they considered themselves attractive or harboured fears that they were nothing special.

I had been wanting to talk to this woman for months, ever since I had moved to the area., but I had never had the chance, only seeing her in the street, sometimes with an elderly woman with a walking stick, who I took to be her mother.

"How old is he?" I ventured, looking at the dog.

"Six months," she replied. "He's a bit mouthy but he's as good as gold really."

"You're looking very athletic," I said, trying to sound jovial. "Going for a run with the dog?"

She looked uncomfortable at the fact that I had observed her appearance.

"It's just a fleece and leggings," she said, "It's comfortable."

"Yes, I suppose so," I said, in retreat. "Looks good, though."

"Listen," she said with her head cocked. "If you're looking for someone to chat up you'd be better off with my auntie. She's about your age."

"I'm sorry," I said. "Force of habit." That was it, the sum total of my defence and I had no follow-up to take it in another direction. I stood there like a fool.

"Ach, don't worry about it," she said. "You're harmless. Probably. Now I've got to go," and she walked past me and down the road. Then she called over her shoulder, "She'll be in the County Inn for dinner about half six."

I got to the County at 6:45, but there was no sign of them. I sat with a pint of the cheapest beer, this being a pub where you could pay £6 a pint if you weren't careful, and if you're on a low income, that can eat up your bank balance shockingly fast.

I was about to give up when, at 7:15, the tall woman came barging in through the front door and walked straight over to my table.

"Had an emergency," she said breathlessly. "She wasn't happy with her aluminium stick so we had to hunt around and borrow a nice one. She's on the way. Get her a Cinzano and lemonade. They keep it specially for her."

"Ice and lemon?" I asked half-jokingly.

"Two slices of lemon and a green olive," she said, looking around the room. "You can nick one from the bowls on the bar. Ah, here she is. I'm Teri. Got to see somebody. Auntie Vi, this is... what's his name." And with that she disappeared into the crowd.

Vi and I shook hands and she sat down. I got another pint for myself and the Cinzano and trappings for her.

"So, you're my date," she said with a grin that had something of the delirious about it.

"Yes, I suppose I am," I said, and we set off on the journey of discovery that you go through with any new acquaintance, whether you have been set up by their niece or not.

Her name was Felicity and she was known as Fliss. She was younger than she looked, just turned sixty-six and the walking stick was because of a long-standing knee injury that needed to be looked after.

"No, I'm not decrepit," she said. "Everything in working order except the bloody knee." She looked at me to see if I had read more into this than she intended.

"Me too," I said. "We're not dead yet, are we?"

"No, although you'd think that from the way some people treat you," she said with feeling.

Thus established as fellow members of the generation that invented sex, we both relaxed into a kind of conspiratorial camaraderie.

Every generation thinks it has invented sex, of course. They can't imagine their parents doing it, let alone grandparents, but it came out of the shadows in the early 1960s to be talked about more openly, where previously most women certainly hadn't admitted they had any interest and men had simply bragged and lied among themselves. In the Sixties came the miniskirt and the contraceptive pill and suddenly there was a bit more honesty and the permissiveness to give people something to be honest about.

By the time Teri joined us, Fliss and I were firm friends, but by nine o'clock she was ready to go home. At a younger age I would probably have tried to get her to get home with me or invite me to hers, but those things clearly weren't going to happen. Instead we arranged to meet for a cup of tea the next afternoon. And yes, I did have fantasies about what we were going to do together when the opportunity presented itself. But I didn't have a wank about it that night because night is the province of young people and I'm better in the daytime these days.

We had a cup of tea and a piece of cake each; these two old codgers in the tearoom must have looked like an old married couple, out for the highlight of our week. That couldn't have been more wrong. I was thinking about getting Fliss's clothes off, having warmed the bedroom up first, of course. She accepted my invitation to go to my house and watch TV. There was a little glint in her eye as she accepted, though, and I knew I was in with a chance.

We walked back along the little river and sat on the bench to give her knee a rest. I touched it gently, as if I were blessing it, and stroked her leg quickly. We both looked around to check there was no one coming and, the coast being clear, I left my hand there and she put hers on top of mine.

Back at my house we sat together on the settee and watched a cookery programme.

"How's the knee?" I asked, giving myself a reason to put my hand on it.

"Fine," she said. "You have a nice gentle touch." I squeezed her knee gently and she looked at me in a way I interpreted as inviting me to go further. I decided to do what she probably hadn't experienced in many years: I put my hand up the old lady's skirt. Again she looked at me with permission in her eyes. I slid my hand all the way to the top of her leg, enjoying the silkiness. When I began to tickle her through her knickers, she sat back, so I removed my hand.

"I didn't say stop," she said, putting my hand back up her skirt. "But you should kiss me too."

How stupid of me. Somewhere in the back of my mind something said the old rules didn't apply, but she was telling me they did. I would have to forget we were two a man and a woman old enough for most people to think we were past it.

I wrapped my arms around her and we kissed gently but deeply. She liked it. I squeezed her left breast and she liked that too.

"Take me to bed," Fliss whispered.

As we reached the bedroom door she asked where the bathroom was and excused herself to "pop" into it for a minute.

I sat on the bed, feeling impatient yet hesitant. Just feel her up, undress her and do what you have always done, I told myself.

"Don't look so petrified," she said. "Actually, do you know what petrify means? I looked it up once when I was doing a crossword. It means to convert organic matter into stone. So part of you can be petrified if you like. Are you petrified in any way?"

"In a good way," I said. "Getting there, anyway."

"Let's get in," she said. "It's a bit chilly out here."

So we both undressed quickly and got into bed together for the very sensible reason that it was cold. We assumed our natural positions, she on her back and I leaning over, kissing her, with a hand between her legs. Her pubic hair was delicate and sparse. Her skin was soft and rather loose, like mine. Her vagina was warm and more than moist, quite slippery. I stimulated her clitoris and she gave m a look that seemed to combine surprise, appreciation and gratitude, as if I had achieved something she had doubted could be achieved at this stage of her life. My penis was hard and eager in her hand. She squeezed the shaft and jerked the skin up and down a bit before taking my knob and just holding it like a prize.

"Are you going to fuck me?" she asked in a low voice.

"I am," I said. "I am going to fuck you. You are a gorgeous woman and of course I'm going to fuck you." She parted her legs further and pulled my cock to bring me towards her.

"Slip it in, " she said invitingly. "I used some lubricant just in case."

Now fully on top of her, I found her hole without even using my hands.

"Mmmm!" she said approvingly, and then the sound deepened and turned guttural as she felt a hard penis enter her. I played with her clitoris some more and then put my fingers between her buttocks. She tensed instinctively but gradually relaxed as I stroked her there. She gazed into my eyes and said, "Come on."

I pumped Fliss steadily and firmly but neither of us was getting the full benefit because the lubricant was not just unnecessary but counterproductive. She wasn't a tight youngster, but a more-than-mature woman and her vagina needed no help in accommodating my cock, which itself had seen enough action over the years and was not as easily excited as it had once been. I put my thumb in there and that improved matters, but we still weren't getting anywhere.

I took my thumb out and plunged it into her arsehole.

"Oooh," she exclaimed. "That's very rude." She paused before adding, "But it feels nice." I concentrated on that, thrusting my thumb deep inside her and bending the knuckle to reach other parts. "Maybe we should do that properly," she said. "Have you ever done that with your cock?"

"Not often," I lied. I don't think it's as common as people make out. "You?"

"My husband was a conservative type," she said. "And you didn't hear so much about anal sex in those days. But if it feels as good as your thumb does..."

I withdrew my cock from her cunt with a slight sense of disappointment, which I'm sure she shared, but without saying anything we both decided that this new thing we were moving on to was something special.

Fliss got on her knees but then thought better of it.

"Bloody knee'll only give me gyp," she said bitterly. "Let's try it on my back."

She lifted her legs as far as either she could or dared. She fished around inside herself for more lube, including her own natural variety, and spread it in her crack and on my cock.

"Come on," she said. "We're going to have a good time."

I pushed her legs up further and held them as I positioned my cock in her dent.

"It's all a question of allowing myself, apparently," she said. "I read up on that once. It's perfectly doable and doesn't hurt as much as people think if you do it right. I need you to be positive and I'll do the same."

I pushed myself forward and my cock entered her surprisingly easily. She gave a little gasp and then began blowing her breath through pursed lips, like a woman in labour.

"All right?" I asked.

"Fine," she said. "Fuck me up the arse, as they say."

I duly fucked old Fliss up the shitter and we both loved it. Not so much the physical sensation from my point of view, but the fact that we were engaged in this taboo act that neither of us had experience of. If her niece Teri were ever to hear about our liaison - and I rather doubted she would - I thought the anal sex part would be withheld. It's just not a very grandma/grandpa thing to do. But Fliss was smiling at me as she received her assfucking.

"You're a very naughty girl," I said happily.

"I am," she replied. "And look at you, doing such a thing to an old lady. The next thing I know you'll be masturbating over me." Taking that as my cue to move on, I withdrew for the second time. Wiping my cock on a tissue, I began to wank and she watched me, fascinated and almost drooling with desire. She lifted her legs again and said, "In there. Everywhere."

I came in copious amounts, in her pubic hair, on her open cunt and right into her anus. Fliss gave a deep growl and grabbed a tissue.

"You'll be messing your bed up," she said in grandma mode.

We arranged to meet again in a couple of days, this time leaving out the tea and cake. Two o'clock came and went but she didn't appear. I tried messaging her but nothing happened.

At 4:30 there was a knock at the door and it was Teri. Fliss had fallen and aggravated the knee and when she fell she broke her phone, so they had no way of contacting me.

I made us a cup of tea and we sat together on the settee and talked. She was more relaxed, more open than she had been in the street, probably because she now had a character reference from her aunt. In fact, she showed no intention of getting up and leaving, so I suggested a glass of wine and she accepted gratefully. Fliss was with her other niece, a nurse who lived a few miles away and had insisted on having her there for the night.

So there I was with the big woman with the imposing body and there was a trace of perfume about her. I started thinking unworthy thoughts. To be precise I was imagining licking her arse, which I hadn't thought her very mature relative would be receptive to.

"You had sex with her, didn't you?" she said, and I searched her words for signs of accusation. Then she smiled.

"That's great," she said. "Just what she needed. She's been bouncing around the house. Singing. Drinking. That's why she fell over."

I said nothing, but my suppressed smile said everything Teri needed to know. Then to my surprise she gave her mound a quick, almost imperceptible scratch with two spread fingers before using the same hand to adjust her bra at the front.

"Give me a hand with this," she said casually. "It's new and it's not sitting right." She pulled her sweater up to reveal her enormous breasts bulging over the cups.

"Take your top off," I said, as a professional might. "Now take the bra off."

"Ooh, doctor," she said happily. "What do you think the problem is?"

"Nothing wrong with the bra, Teri," I began. "The problem is that your breasts are so beautiful, they shouldn't be cooped up in there. I would recommend having your nipples sucked."

"Oh yeah? By who?"

"I can do it for you right now," I said, and she sat back to let me at them. I licked them each in turn and sucked her nipples, which grew hard and stood out proudly.

"In fact," I said, enjoying the role play that allowed us to behave in this way, "I think you need to be licked all over."

"All over?" she asked.

"Yes," I said with mock seriousness. "I am going to lick your armpits and your vagina and then I want you to kneel on all fours while I lick your anus."

Teri flung herself at me and we kissed haphazardly while wrenching our clothes off. I pinned her left arm back and licked her armpit.

"Shit," she said. "Are you sure you're a real doctor?"

"It's alternative medicine," I assured her. "Some of it, anyway. Spread your legs so I can reach your..."

"My minge?" she offered. "My cunt?"

"Exactly," I said.

She tasted and smelled quite strong down there, not unclean, it was just her. Her pubic hair was shaved into a little heart shape and all around her labia she was smooth. I licked her slit, poked my tongue into her hole and sucked her clitoris and piss hole. She writhed in ecstasy.

"I want to suck your penis," she said, and I was delighted that she had reacted like that. It's a characteristic of good lovers to want to give as much as they receive. Those who lie there and let themselves be done are missing out, although those of us who like to give are more than happy to oblige. But when a woman not only wants to suck you but actually asks to do it, that's when you know you're in for a good time.

Teri took my cock in her mouth with tenderness. She clearly loved doing it and wasn't ashamed to let me know.

"I've always wanted to suck you," she said. "I don't know why, but I could see there was a sexy man underneath that warm jacket and silly hat."

"And I've always wanted to lick your arse," I replied.

"Well, you'd better do it, then," she said, getting into position, her neat little brown eye exposed to me.

I licked her tenderly, gently, exploring in detail that treasured little area. She moaned with dirty, lustful pleasure. It's a different kind of sound from when you do other things. A woman with a determined face between her buttocks and a tongue adoring her moans as if she has reached the depths of depravity and accepts her place as the utterly debauched woman who might once have been innocent but has now gone completely, irreversibly over to the other side.

"You're a dirty sod," she said contentedly.