I work in IT for a large company. Pam (name changed) is the Faciliites Manager for our office (although she works in another building). She is in her fifties, but looks after herself and is always well dressed usually in skirt suits. I started to flirt with her after fixing her laptop and finding that she had visited various swinging websites. It started off with little comments, which she responded to well. At the Firm's Christmas Party we had a quick grope and a kiss in the cloakroom but couldn't do much more as we both had our partners with us. From then on things have escalated and we are regularly IM'ing each other whilst at our desks. Last week I was sitting at my desk when an IM popped up from Pam "I'm feeling Horny!" I chatted with her and asked her what she was wearing, Pam said that she was coming over for a meeting and would show me! My heart was thumping. About an hour later Pam breezed into the office in a black skirt suit, white blouse, dyed blonde hair tied back, black stockings and black patent heels. She turned a few heads on the way to my desk. She said Hi and then leaned over and dropped a pair of black satin panties into my lap and whispered "Put these on for me and meet me on the 4th Floor in 10 minutes" I could feel myself blushing as she turned and left towards the lift. The 4th Floor was being refitted and was empty at the moment, there were a few offices up there and normally deserted. I waited 5 minutes after she had left and then went to the toilet. Once in a cubicle I examined the panties. Pam had obviously been wearing these as they were still wet from her juices. I changed out of my boxers and slipped them on, my cock straining against the black satin and leaking pre-cum onto them. I pulled my trousers back up and headed for the lift, thinking of what the knickerless Pam had planned for me on the 4th Floor? The lift doors opened and there was Pam talking to the Managing Director and 4 other Department Managers about the progress of the refit! "Ah - here is John from IT, maybe he can answer some of your questions?" I just wish the floor would open up and swallow me. There I was standing infront of my Managing Director with Pam's black Satin knickers on under my suit trousers! They all turned towards me and Pam shot me a cheeky wink. I stammered through the 1st few questions. Pam closed the questioning saying how helpful I had been to her and that she wouldn't know what to do without me. Pam ushered the party through the office to the rear exit but then made an excuse and came back to me and said "Ladies Toilets now! I need my Panties back" She winked and returned to the party. I made my way to the toilets adjacent to the office and checked around before slipping into the ladies and hiding in a cubicle. About 5 minutes later I heard someone come in, my heart was thumping! "John, it's me Pam" I opened the door, there was Pam with a huge grin on her face. I started to tell her that it wasn't funny but she raised a finger to my lips and said "shhh!" When I shut up she grabbed me close and we kissed our tongues probing each other. She pressed me against the counter and one hand reached down the front of my trousers "oh you did wear them, mmm". I rucked up her skirt and traced her suspender belt with my hand up to her shaved pussy "mmm, they are today's then". I strated to rub her clit which was already soaked after about a minute I had her moaning and biting my lip and neck. She then started to unbuckle my belt, soon my trousers were around my ankles and she had my cock in her hand, wanking me in her black satin panties. She then pushed my onto a chair and straddled me, guiding my cock into her dripping wet cunt with her hand. She slowly lowered herself down my length "mmmm, bigger than I'm used to" she said. She then rid me like a woman possessed, unbuttoning her blouse and lifting her breasts out of her bra so that I could bury my head into them. We both came together, our hot sweaty, sticky bodies embraced. After a minute or so, Pam lifted herslef of me and started to button up her blouse, I looked down her black panties were hooked below my balls thick and sticky with cum. "Would you like these" I said "keep them as a souvenir" she said. I tucked myself in and tried to sort myself out as Pam straightened here hair in the mirror and reaplied some lipstick. "That was so naughty and horny John, we will have to do it again soon" She kissed me on the cheek and then left. I can't wait for a repeat performance.