When our baby was born my wife's parents very generously offered to pay for an au pair to help us out. As with everything else Catherine was very choosy when it came to employing the right person. She interviewed four possibles, two young girls, a mature woman and a man. I was most curious about the man. It seemed an unusual line of work and I had a lot of sympathy for him, after all not many women would trust a guy in his early twenties to care for their baby and do all the housework. I was allowed to sit in on the interviews and ask a few token questions. Catherine must have come across as pretty demanding, she was very clear about the strict rules she intended to follow. Unfortunately the two rather attractive girls didn't make it to the end of their interviews. The older woman was more professional but thankfully she rejected the offer. I thought David was a star, polite, serious, knowledgeable on everything concerning babies, even Catherine appeared to soften when he agreed to sign her five pages of contract terms. So it was that David Haliday came to live with us in our five bed semi in the suburbs as live in nanny and housekeeper. I immediately took to David, he was hard working and cheerful with it. He was easy to talk to, very open and not at all cynical like me. I started to have my lunch with him in the dining room. If Catherine was working late I would invite him into our living room for a drink after dinner. He told me about his family, how he dropped out of university and drifted for a while until he met his girlfriend Natasha who had encouraged him to do child minding and nursery work. One evening, after we had drunk most of a bottle of wine and were lounging about on the sofa, I started moaning about Catherine saying how she was never around and when she was she had no time for me. I was just looking for a bit of sympathy really and hoping David would tell me some details about his sex life with Natasha. I was a bit taken aback when David started asking what sort of things Catherine enjoyed in bed. To be honest it was hard to think of anything she positively enjoyed. “Maybe you're just not doing it right, David laughed, “what she needs is a it of novelty, woud you like me to give her a good ride?” I nearly choked on my wine. He apologised immediatley then like a wise old sage he assurred me that most middle married aged women pretended not to be interested but if the right opportunity arose they seldom said no. I wondered If he was speaking from experience. I changed the subject. Lying next to Catherine in bed that night I remembered what David had said. He was probably right of course, he would know how to pleasure her. It would be good for her. I wondered if David was thinking the same as he lay in his single bed in the room above our heads. She would never do it of course, I was certain. I couldn't imagine her letting anyone touch her. The following day was hot and humid, I had to work in the garden while Catherine had a day off and took the baby to the park for a picniic with her mother and baby friends. After a morning of digging weeds, planting and watering I had to come in for a glass of water. I decided to change my tee shirt. I struggled up the stairs and crossed the landing to our bedroom. The door was was open a few inches and I was amazed to see David with his back to me standing by Catherine's wardrobe, he appeared to have been examining her clothes. “David, I'm not sure you should be in here.” “God” he startled, “I'm so sorry, I wasn't touching anything I promise, just admiring this dress Catherine was wearing the other night, I think Natasha would love it.” “Well you should have asked Catherine.” “I know, I just didnt think, I'm so sorry, you wont tell her will you.” I didnt know what to say, I didn't believe him for a second but nor did I want to see him sacked which Catherine would certainly do if I told her. I decided to indulge him a little and see where this would go. “OK, be quick, I wont tell her.” “Really” he mumbled “oh brilliant ” He reached inside the wardrobe and scooped up a long green silk dress on his arm, running his other hand under it he raised it to the light and let it drop. I could feel the excitiment in his touch, we both knew he was doing more than admiring the dress. He held it up to himself as if measuring it, pulling the waist in. “Very nice, you would look good it that”, I joked, half hoping he might agree. “It is beautiful, If Natasha wore this I would refuse to let her put any underwear on, its so sexy.” He thrust out his hips rubbing the dress over his crotch. “Do you like that?” “Oh yes,” I felt my face redden. I reached out and stroked the dress against his hips. “Why don't you slip it on now, just so we can see?” “You mean it don't you”, he said, looking like a child on Christmas eve. He eagerly handed me the dress, pulled off his tee shirt and rather primly turned his back as he undid his jeans and dropped them to the floor. He hopped about pulling his socks off. I waited for him to take his underpants off next but instead he pulled the dress over his head and stood admiring it in the full length mirror. He looked stunning. I came up behind him and put my hands on his waist then squeezed his firm bottom. “I think there is something else you might like” I whispered in his ear. He quivered in my arms, guessing what I meant, “Oh yes I would like that.” We moved over to a chest of draws and I pulled open the top draw. Inside was a confussion of underwear, bras and panties. His eyes lit up. “Go on, its OK,” I assured him. David reached into the draw and pulled out one after another the intimate garments, stretching them over his fingers, and laying them carefully on the bed, looking at me for approval as he did so. I could hear both of us breathing heavily as he held up each of Catherine's panties for us to examine. “Do you mind?” he said holding a pair to his face. “Of course not, I want you to enjoy them, here let me help.” I kneeled in front of him and reached up stroking his legs under the dress. His bulge felt enormous cupped in my hands. His erection pushed the green silk out in front of him and I had to pull hard to get his underpants down over his cock. When he was free he lifted the dress to proudly display himself in front of me. He bunched up the knickers he was holding and wrapping them round his penis began to wank in front of me. He used long slow strokes. My face was so close I could smell the pre cum dripping onto his hand. I pulled out my own penis and David handed me a pink cotton pair of knickers from the draw to wank with. The excitement was too much and almost immediatley I felt myself ready to cum. “I have to cum”. “That's OK, me too” and we sank onto the bed side by side furiously rubbing our cocks in the air groaning in unison as we orgasmed. We turned to each other exhausted, laughing and admiring the pools of cum soaking into my wife's underwear.