We didn’t really have a special name for it in the late 1970s. If we’d had one, it wouldn’t have been anything like “Twixmas.” It was just the week between Christmas and New Year. I’d gone along on that Tuesday evening, a bit grudgingly, to my girlfriend’s family gathering at her aunt’s house.

“Mum looks happy for once,” Jaq said. She was curled up on the sofa next to me with her head on my shoulder. “Are you OK?” she said. “Do my family all seem weird to you?”

I squeezed her, my hand cradling her pert, bra-less breast through the sheer, dark blue dress. “They seem like a nice bunch; your aunt Lizzie is very similar to your mum, isn't she?”

“Apart from the different coloured hair, bigger boobs, and being three inches taller, you mean?”

“There’s such a family resemblance. It's like you and Jay, obviously sisters, but quite different.”

“I’ll bet you secretly fancy Lizzie.”

“She’s almost twenty years older than me! You look a lot like your mum; Jay is more like Lizzie.”

“You fancy my mum, then? Careful how you answer.”

“She does look pretty good in that black dress.” I looked across the room at the slim, petite woman with long brown hair, and realised she did look incredibly good. The dress fitted her in all the right places. She noticed me looking at her and smiled back, her green eyes sparkling.

“Git,” Jaq dug me in the ribs and brought me back to reality.

“Mind you, you'll look even better out of yours. You look fantastic, you know that. I don’t think you’re wearing much underneath that dress. That bloke over there seems to have noticed, too.”

“He’s a really dirty git; he’s been trying to see my knickers all evening.”

“The male half of the room all have, and most of the women have been trying to work out if you’ve got any on.”

“I’m not a complete tart. They are tiny, though. I expect you’ll find out later.” Our joking ended abruptly as we, and everyone else at the family party, heard shouting from the kitchen.

“...leave me alone, you dirty bastard,” was followed by a loud shriek and an unmistakable slap.

“That was Lizzie,” said Jaq, jumping up, smoothing her dress down and following her mother out of the room all in one fluid movement. “Stay there.”

A few minutes later, Jay rushed into the room. I could see Jaq in the hallway, her mother crying on her shoulder. Jay came over and absent-mindedly I put my arm around her, drawing her more closely than I had intended, and touching a breast. “Stop that, you idiot; wrong sister; wrong time,” she hissed in my ear as I tried to turn the bungled attempted embrace into a conciliatory gesture. “It’s gone totally tits up; I need you to take Mum home and wait with her while we try to sort this mess out.”

“What’s up?”

“Don’t ask, just help me, help Jaq, take mum home, NOW.”

Jaq and Jay’s mother were crying as Jaq helped her into her coat. “Just go home with Matt, we’ll be along soon.”

“Come on Mrs R,” I said quietly. She leaned on me as we walked to my car.

We were ten minutes into the half-hour journey before she spoke. “He hasn’t fucked me in three years; he’s always too busy with his tarts; now he gropes my sister. Can you stop for a minute? Please, I need some air.” Stunned by her outburst, I pulled in at the next layby. We were in the middle of nowhere, in the pitch blackness of a December night. I jumped out and opened her door. She leaned on the little car, then on me. She sobbed for a good five minutes. “OK, ready now. Top down?”

I resisted the puerile response and reached into the car to unlatch the hood. I opened the door, and she got in. That can’t have been a deliberate flash of stocking top, can it? That’s small two seaters for you. I told myself to be serious for once.

We drove on, heater on full to cope with the cold night air. “Talk if you want to, Mrs R.”

“It’s Carolyn, you know that; and that moronic piece of shit of a husband of mine is Gwyn, but you can call him “nasty lecherous bastard” for all I care.’

We drove on in silence for another few minutes. “The drunken half-wit is interested in anyone in a skirt except his wife. What’s wrong with me?” She started to sob again.

“He’s a fool. I think you’re lovely.” Where did that come from? It was true, she always looked good and could pass for Jaq and Jay’s big sister.

“You don’t have to flirt with me out of pity. You treat Jaq well, and that’s all I can ask, especially after what Jay did to you. She turns after her dad by the looks of things.”

“No, I mean it. You can see where your girls got their looks.”

She half-smiled through the tears. Where she’d slumped in her seat, she was now showing a good eyeful of lace and silk knickers to go with her stocking tops. It didn’t seem to worry her. “Eyes on the road, please. My legs will still be there when we get home.”

The phone was ringing when we got back to the house. Carolyn rushed inside and answered it. “Don’t worry Jay. We’ll see you in an hour or so. Yes, I’ll ask him to wait with me.”

“Can you wait until Jay gets here with the others? She’s got her dad’s car. He’s disappeared, probably to the nearest pub, or one of his tarts.”

I made coffee. She was standing behind the sofa with her back to the door. I put the mugs on the table. I have thought about the next part many times over the years, and I still have no idea what made me do what I did next. I stood just behind her and placed my hands on her waist. She tensed for a split-second, then relaxed. I kissed her gently on the neck. She sighed quietly; life had already got so much more complicated. I added to that by slowly lowering the zip on the back of her dress, inch by inch, placing butterfly kisses on her soft skin as it came slowly into view. This was the moment when I learned the difference between girls and women.

Gently, I undid the clasp of the black lace bra and savoured that wonderful moment as gravity took over and her breasts sagged slightly forward. I kissed the red mark on her back and slid my hands inside her dress to caress the soft, smooth skin of her swelling orbs. Her nipples hardened rapidly, like small bullets as my fingers circled, then squeezed them. I was captivated by the sensual softness of her skin and fought my baser instincts. Now was the time to go slowly.

I felt her body tense. She turned. I thought for a split-second that she had come to her senses and was about to push me away, or worse. Instead, she lifted her head and kissed me hard, before she pulled away again slightly and slowly lifted the black dress over her head. She stood in splendour, now clad only in tiny black silk and lace knickers and sheer black stockings. She steered my hands back to her now-bare breasts, closed her eyes, and sighed.

“Not here,” she whispered, then turned away from me towards the door. I followed her upstairs, captivated by the view of her small, curvaceous backside just in front of me. We turned into her bedroom. She stood with her back to the bed, and we kissed again. I ran my hand between her small, round breasts, to the soft downy skin of her stomach and onwards to the lace edge below. She stepped back, lowering herself on to the edge of the bed, feet either side of me on the floor.

“You need to catch up.” She leaned forward, undid my shirt buttons, then my belt, and finally my trousers. I shed my clothes easily, leaving me standing in front of her in just my boxers. I dropped them to the floor, stepping out of them.

Her eyes were drawn to my rock-hard cock. She reached out and stroked it, then cradled my balls, gently massaging them. “Now,” she whispered, lifting herself from the bed and removing the tiny gossamer silk and lace fragment. She moved further onto the bed and wrapped her lovely legs around me, drawing me towards her. “Fuck me, but gently, please.”

I eased myself between her swollen, welcoming, wet lips. She held her breath as I moved slowly into her, as I experienced that incredible hot knife through butter feeling as her silky soft, warm, neglected pussy yielded. She tensed, relaxed, then tensed again as I moved deeper with each stroke, gradually quickening the pace. I felt her small, soft hands pressing on my back and her legs tightening behind me, pulling me ever closer. I drove faster and harder as she bucked and thrashed beneath me. She screamed “yes” as her muscles tensed. It was like being inside a living vice. There was no way I could last for long. I drove hard right up to the hilt, then exploded deep inside her.

We lay there, panting for what seemed like an age. I noticed she was crying softly. I kissed her gently. “You are so lovely. I’m sorry.”

She turned slightly to look at me. “I’m not. That was wonderful.” I kissed her lovely breasts, then around her perfect neck and up to those soft lips. “No time. We need to be ready for when the others get here. I’m going to shower; you clean yourself up and go downstairs.”

Reality returned. When she came downstairs after her shower, she was dressed in a blue crew neck jumper and black jeans. With her long hair tied back into a ponytail, she looked more than ever like Jaq’s big sister. She curled up next to me on the sofa. “I need to tell you something, well several things.” I pulled her closer and kissed the top of her head while fondling her unconstrained breast through the fabric of her sweater.

“First, if you ever cheat on Jaq other than with me, I’ll rip your balls off.”

“Say what you mean, Carolyn, stop beating around the bush.”

“Look, this is difficult for me. In the space of an evening, I’ve seen the end of my marriage and started an affair with my daughter’s boyfriend.”

“This is an affair, is it? It’s not a one off?”

“It had better be. Look, this is tough enough for me to explain already. You are only the second man I’ve been with.”

“Bloody hell.”

“Be quiet for a second. I meant it. That was the first time in years for me, and it really was the first time for me outside of wedlock. That bed was new three years ago, and it’s never seen any action before, at least not while I’ve been there.”

I squeezed her closer. “You really are special, you know.”

We heard a car outside, and I got up to go to the kitchen to make drinks for the others.