It was towards the end of July - the start of another 6-week summer break for schools and colleges. Another 6 weeks of just mooching around, filling time, doing whatever shifts I could get at my part-time job and waiting for the few friends I had to come back from their family holidays to various places either abroad or elsewhere in the UK.
We wouldn't be going away - we hardly ever went away on holiday. My parents couldn't really afford holidays and I didn't have the money to pay for my own. At 19, I had just finished my first year at Technical College studying an engineering course. I had a part time job stacking shelves in the local supermarket that paid enough for me to buy clothes, go out occasionally with my friends and maybe even have the odd date with a girl if I got that lucky - it certainly wouldn't stretch to any sort of holiday.
I am Adam, and in the mid-1970's I lived at home with my parents and my 18-year-old sister Mary. Mary had just finished her final year at school and was planning to start at College in September to do some sort of secretarial course.
We lived in a small 2-up/2-down cottage style terrace house on the edges of North London. It was a small house - 2 bedrooms upstairs for my parents and for me. Downstairs there was a front lounge, a former back parlour that was now used as a bedroom for my sister and a narrow rear extension that housed the kitchen and through that, off a small lobby, was the family bathroom.
In years gone by my sister and I shared the 2nd bedroom upstairs and the back parlour was used as a dining room but once I reached 14 or 15 my parents felt we should have separate bedrooms and so the dining room was turned into Mary's bedroom and the dining table was squeezed into the kitchen.
We didn't have much money - my parents worked hard but it seemed they only just about made ends meet. My father worked long shifts and every hour of overtime he could get. My mother worked in the local hospital and also had a part-time evening job in an off-licence. This meant that Mary and I were very much latch key kids - letting ourselves in after school and fending for ourselves until our mother got back from her day job to make us our supper before she rushed off again to the off-licence. We weren't neglected - very much the opposite - but it did mean we grew up creating our own entertainments and by-and-large fending for ourselves.
Neither of us had many friends - we couldn't have friends round after school as my parents wouldn't be there and we therefore didn't get many invitations to visit other kids houses. So we entertained ourselves and, not knowing anything else, were generally happy and content.
At 19 I had had a few girlfriends but nothing serious. I was no longer a virgin although the fumbling and inept manner of losing my virginity a couple of years previously was more embarrassing than pleasing. But I had no current girlfriend and hadn't had one for several months. I therefore relied heavily on my trusty right hand and my imagination to fulfil my sexual needs.
I guess I was an average type of guy - about 5 foot 10 inches tall, slim built, not bad to look at but not, in my eyes, anything special. My sister Mary had always been rather plump - she was slightly overweight and already had a big frame so she was what you would call curvy. She had quite large breasts and a much bigger than average bum - a bum that had been the subject of a lot of my fantasies over the last few years. Like me she had a pleasant face but would not have won any prizes in a beauty contest.
Mary and I had always got along well - we had spent so much time together throughout our childhood, especially through school holidays when we were at home most days whilst our parents were working, that we had learned how to amuse ourselves and rub along well enough. Things had grown a bit strained between us over the past year but I put that down to normal growing pains! But whether she knew it or not she did also provide me with most of my sexual fantasies during my puberty and beyond.
There were times during puberty, especially in the later years of us sharing a bedroom, when I snatched the opportunity to get a sly look at her getting dressed or getting ready for bed. These glimpses of her developing body - and especially that large rear end - gave me plenty of fantasy material for those early masturbation sessions. However since she had moved to her downstairs bedroom the chances of grabbing any sight of her naked or semi-clothed body were greatly diminished, although I did still occasionally get a sneak look through the door jamb if she left her bedroom door ajar and sometimes I got an odd flash as she walked through the kitchen from the bathroom wrapped only in a towel.
And so the summer holidays were already 2 days in. Our parents had gone to work, and I was sitting in the kitchen in my pyjama bottoms and a tee shirt reading a book and having a coffee. Mary walked through on her way to the bathroom wearing her dressing gown and carrying a towel.
"Hi Sis. Don't be too long" I said. "I need to grab a shower as I am working at the supermarket this afternoon."
"Okay, no problems" she replied. She went into the bathroom and there was nothing she said or did that was out of the ordinary but for some reason I felt the bulge between my legs stir slightly. Like all guys of that age I was always a slave to my cock and its needs. I reached down and lightly stroked it, feeling the tingles run across the head of my cock and causing my balls to tighten.
I slipped my fingers into the fly hole in the front of my pyjama bottoms and rubbed my cock with more intent. It started to grow as the blood flowed into it and I knew I would have to knock one out to relieve myself. Should I go up to my room? "No problems" I thought, "I've got time to do it here before she finishes in the shower."
I pushed back my chair and opened my legs so that I could get at my cock through the fly hole. Grabbing my shaft in my right hand I started to smear it with my pre-cum juices and I cupped my balls in my left hand - lightly squeezing as I pumped away.
I closed my eyes and started rubbing faster on my cock, feeling the spunk starting to collect at the base of my shaft as I worked towards orgasm. I was thinking of Mary and blending together all the times I had seen her body over the years and imagining what she looked like now she was virtually fully developed. I was getting closer and closer to coming when all of a sudden I heard the latch on the bathroom door click open - OMG she was coming out and would catch me!!
I scrabbled to get my cock tucked away into my pyjamas and just about managed it before Mary appeared in the kitchen - with her dressing gown on and her hair wrapped up in her towel. I was half doubled over in my chair trying to hide my erection and was seriously discomposed. Mary looked at me puzzled.
