All persons engaged in sexual activity in this story, are over 18 years of age.
This story took place in the 1970s in the United Kingdom when the 'World Wide Web' or Internet as it is known today, was barely an infant and not available to private individuals. As for mobile phones, they were only at an experimental stage. This meant that knowledge of sex was gleaned mostly by chats with 'experienced' friends or looking at adult magazines aka Playboy, Penthouse, Hustler and so on.
Boys and girls were nowhere near as mature or knowledgeable about sex at age 18 compared to many of today's 14 or 15 year olds, thanks mainly to the multitude of internet 'information' that can now be accessed by anyone that can type 'sex' into a search engine.
All of this is to set the scene for you, to make you aware that in the 1970s, unlike the present, many boys and girls at age 18 were considerably naïve when it came to real sexual encounters.
*
The last two days had been a bit weird with my sister Sue after our little 'unintentional interlude' on Wednesday afternoon, in what I had come to regard as 'my' shed. From accidentally catching me reading 'adult magazines' in there, she had threatened and then persuaded me, to let her see and hold my cock, while in return, I had seen, and felt up, her bare tits. The 'cock holding' had turned to stroking and eventually, although not intentionally, led to her making me cum and covering her shocked face and her breasts with my sperm. I had used those memories of her stroking my cock and the images of her firm breasts for numerous wanks over the last few days. In fact, my cock was becoming a little tender from all the attention I had been giving it.
Sue hadn't spoken much to me since then but had given me odd looks from time to time and Mom had picked up on it, asking if we had had an argument or something, so things were a bit awkward.
I wondered if, with hindsight, she wished it hadn't happened and perhaps wanted to just forget it.
I was in two minds. On the one hand it had been an unexpected and erotic experience that was still giving me fuel for great orgasms, but on the other hand, it was my sister, we shouldn't have gone so far and I didn't want it to affect our normal relationship.
After she came home from her work in the hair salon on Friday evening, I managed to catch her alone in the kitchen area preparing some vegetables for our evening meal. Mom had asked her to do this as she was going to be a little later than usual. I could hear Dad in the bathroom upstairs.
I sidled up beside her at the sink, "Is emmmm.. everything ok Sue?" I asked quietly.
She didn't look at me, "Yes, I think so," she replied.
"You only 'think' so, what does that mean?"
"I have been waiting for you to say something...you know, about what we did, it's been on my mind, but you didn't."
"Oh, well I kinda thought... you...errr.. might want to forget it," I said.
"Do you Ben?"
"Do I what?"
"Want to forget it," she said, in an exasperated voice.
"I don't think I can, easily, it was...uh, a bit ....emmm, exciting I thought," keeping my voice low, "what about you?"
"I thought it was too, and I keep thinking about it but...."
"I know what you are going to say, we shouldn't be doing it, is that it?"
"In part," she turned to look at me with those big brown eyes, and started to blush, "but....well...I didn't know if you might want to ...do something again ...or not."
I felt my cock begin to swell at the thought of doing something more with her, but it was risky.
"Does it emmm.. make you feel tingly just talking about it now Sue?"
"It does a bit," she whispered, turning away and starting to peel the vegetables again, but there was a slight tremor in her hands.
She carried on peeling and chopping even when I put my hand on her back and gently massaged it. I felt her bra strap under her top as I ran my fingers down and up. She stopped then and rested her hands on the front of the sink.
"Mmmm that's nice Ben," she said quietly.
After what was probably only a minute or two, I had established a route all over her back and shoulders with my hand. Just the act of touching her like this had my cock reaching almost full erection in my shorts. I became bolder and let my hand drift down over her short skirt. She allowed me one feel of her skirt clad, tight bottom.
"No, stop Ben, we can't do that here, Dad will be down in a minute and Mom is due soon," she admonished me, turning and moving sideways, so my hand fell away.
"I'm sorry," I said, "I just got carried away, it's just it's so nice, just touching you."
"Yes, and I liked it too, but we can't." She looked down at my bulge, "And I think you need to go do something with that before they are here," she said, a little grin creeping onto her flushed face.
Just then we heard the toilet flush and the bathroom door open upstairs.
I didn't want to bump into Dad on the stairs with my erection tenting my shorts, so I started to head for the garden until it had subsided.
"Ben," Sue whispered, just loud enough for me to hear, "I may have to check if you are studying in your shed on Sunday, when they've gone visiting grandma."
I knew it was going to take a little longer for my erection subside now, but I also knew everything was ok between us.
**********
I did some work on tidying the garden and mowing the grass to keep me occupied on Saturday, as the day seemed to drag on and on. The thought of what might happen on Sunday with Sue kept going through my mind and I had to find some privacy for at least one wank. I didn't see much of Sue on Saturday as she worked all day and then went out with friends in the evening.
On Sunday, instead of the usual roast lunch, we had a simple meal as Mom and Dad wanted to leave around 2pm to visit our elderly grandma some distance away. I kept meeting Sue's eyes over the table and she demurely looked away quickly each time.
"I don't know what's up with you two," Mom said, looking at each of us in turn, "whatever has gone on between you, you need to sort it out. We won't be back until this evening, so you had better behave while we're away and please don't annoy the neighbours with loud music or anything. Is that clear?"
"Yes Mom," we said, almost in unison.
"Ok," she said, "getting up from the table, "don't forget to do the dishes and we'll see you later."
We cleared the table and Sue washed while I dried the few plates and dishes, then put them away.
We heard the car drive away just as we had finished.
It was another warm day and I was only wearing a tee shirt and loose shorts. I noticed Sue was wearing a light summer top and a sort of flared skirt that came to just above her knees. It too was loose and swished about as she walked. She was as usual in sandals with bare tanned legs.
We were both a bit shy and awkward around each other now that we were alone, and both of us were reticent to bring up the subject that was on both of our minds.
After we had exhausted any tidying that we could do, Sue eventually said, "I am going to my room for a while to sort out some laundry, what are you going to do, go to your shed as usual?"
"Emm yes, I guess so, I have a few things to fix," I said, playing the game.
I went off to my shed, leaving Sue to do whatever she was going to do and wondering if anything was going to happen between us, or had she had some second thoughts.
For about a half hour, I had been in my shed tinkering with an old clock that didn't work, gradually taking it apart and trying to see what was wrong. I must admit that I had got engrossed and was sure by now that my sister had found something of her own to occupy herself.
I was slightly startled out of my concentration when I heard a couple of sharp taps on the window. I looked round and saw Sue's face there. I went to the door and drew back the bolt that I use to keep it closed and opened the door.
"Hi there," Sue said, "can I come in then or am I interrupting something?"
"Err....no, .. yes, of course," I stuttered, surprised to see her.
She walked in and stood looking at the parts of the clock on the workbench.
"I see you're doing something useful then," she said, cheekily.
