One of my work colleague is a married lady called Katherine. She's your noramal middle age office worker in her late fourties. I think that she's fortyseven. On the face of it there is nothing remarkable about her. She's a pleasent person to work with, good at her job and I'm sure that she was a loyal wife. I say 'was' because of something which happened last week...and this is true! I'm a red blooded man approaching the big four 0 later this year. I'm have been married to Debbie for the last ten years and things are OK. But that's just it they're OK, nothing too exciting. We plod on. Our sex life is occassional to say the least but when it happens it is good so I haven't bothered to look for anything elsewhere. There is one thing about me thought and that is that I have a hugh fetisch for mature ladies who where nylons. Tights or stockings it doesn't seem to matter. That brings me back to Katherine at my work. Katherine is I would guess a larger size twelve. Very smart in her appearance. She always and mean 'every day' she wears a conservative skirt suit or a dress and jacket to work finished of with nylons and 'sensible' hight heels. Ever since she was transferred to my area I have had the hots for her. Maybe it's the way she just gets on with her job totally unaware of the hardness that she arouses in my pants as she innocently walks about the office. May be it's the way she crosses her legs under her desk or that time that I walked behind her up the stairs the other day listening to the russel of her nylon clad thighs slidding against each other. What ever it is she for me and many times now I have had to have a longer than normal visit to the mensroom just so that I could come back and concentrate on my work!! Last Tuesday the classic senario evolved. A project that we were working on together had fallen behind schedule and it bebcame clear that to get things done we would have to work together late that evening. As I've already said Katherine is very good at her job and she took control of the problem. This only served to incrase my admiration of her. My desk is just to the side of her and the sight of her sitting there in her grey dress and jacket, her crossed legs forcing her skirt to ride up revealing a good four or five inches of thigh as she tapped away at her key board. I just could not cocentrate. Slowly I began to rub my penis through my trousers under my desk. What the hell was I doing.....What if she turned round. My problem grew and grew as I observed her from the side. Unexpectedly she slowly turned round on her chair to ask me a question. It was too late to compose my self and I guess that she must have noticed that I was not exactly fully involved in the companies work! Still in work mode she came over to my desk initially to ask me a question. She stood beside me and it became obvious to her that I had not been doing much work due to my blank computer screen. 'What have been up to' she asked. 'We are supposed to be doing this together! All you seem to doing is watching me'. Her matronly manner and close proximatory hightened my excitment and my by now fully erect cock was throbbing, pulsing inside my suit trousers. I glanced up at her...She had noticed. She had a slightly embarrassed look but it was obvious that she had seen the tent in my trousers. I swivelled on my chair slightly so that my knee gently brushed hers. She did not move away. It's now or never I thought to myself. As she was still pretending not to be aware of what was happening I slowly stroked the back of her calf with my finger tips. She shook slightly as she allowed her self to succome to my unexpected attention. OMG I couldn't believe it as she stood there as I gently slid the palm of my hand up the back of her knee, up the back of her thigh and up, up her skirt. 'We shouldn't be doing this' she said. 'Then, stop me' I replied...She didn't. She placed her hands on my desk to support herself as I moved behind her still sitting on my office chair with both hands I pushed her skirt up to revaeal her nylon covered panties and began to slowly lick and kiss her gorgeous arse throught the nylon of her tights and knickers........(to be continued)