As the train pulled out of the station on the ride home from yet another Groundhog Day at work, I closed my eyes and allowed my mind to drift, once again, to my fantasy lover - my wife Julie’s sister, Helen.

Her auburn hair, her gorgeous smile with that flirty glint in her eye, her pert boobs, her flat stomach, her curvy bum, her long, slim legs ... I began my favourite fantasy, and as I started to undress her in my mind, I imagined I could smell her perfume...

Don’t get me wrong - this was all harmless fun - I could never, ever, actually be unfaithful to Julie. After so many years of marriage, though, who doesn’t fantasise that they’re actually making love with someone else, when doing the deed with their long term partner? ... and don’t all blokes fancy the pants off their wife’s sister, anyway?

By coincidence, Helen was staying with us for a couple of days, so that she and Julie could have some girly time together - shopping, latte, shopping, Prosecco, more shopping - you get the score.

As my fantasy unfolded the ride home went all too quickly, and before long I was walking home from the station with a spring in my step.

As I reached the house, Julie’s car wasn’t on the drive - tut tut, they’re still out shopping, I thought - so when I went in and closed the front door behind me, I was pleasantly surprised to hear Helen’s voice.

“How’s my wonderful brother-in-law?!” - her sultry, flirty Welsh lilt stopped me in my tracks.

As I walked into the kitchen, Helen was standing with her back to me at the sink washing some dishes, staring back at me in the reflection of the window. “Julie’s had to go to Bath on an errand, something to do with work - she called a few minutes ago saying the traffic was awful, and she won’t be back for at least another hour - she asked if I could entertain you!” she said, with that sexy voice and flirty look in her eye.

She was wearing a loose fitting cream jumper over faded blue jeans, which showed off her figure perfectly. My little fella was stirring, getting ready to stand to attention.

“Well, that’s a lovely thought!” I said, returning the flirty look, my mind secretly wandering back to places it had already been once tonight.

As I stood behind her and went to kiss her on the cheek, she said “ooh, there’s naughty!” and moved her head to one side, exposing more of her creamy white neck. I couldn’t resist planting a kiss on the side of her neck, savouring the sensuous smell of her perfume mixed with a hint of coconut shower cream, as I put my hands around her waist, and across her stomach. “Mmmm that’s nice” she whispered, leaning back against me, and putting one hand behind her back.

I slowly kissed her neck again, and the kiss turned into a series of gentle, half-kiss, half-bites, the tip of my tongue tasting her flesh. Moving left as far as her ear lobe, then slowly back down her neck and shoulder, as my hands moved under her jumper then upwards, cupping then gently squeezing her breasts, flicking my thumbs over her nipples, which I could feel through her bra.

I withdrew my right hand, sliding it down over her tummy, inside her jeans, and on, inside her panties to the promised land. “Hmm, you’re a bit damp down there, have you been clumsy with the washing up?!” - no sooner had I said it than I realised how stupid it sounded. “I’ve just been thinking of you!” she whispered. As my fingers explored I could feel just the tiniest tuft of hair on her mound, then the long, moist crease of her lips.

I gently and slowly ran my middle fingertip down her lips, starting over her clit, then all the way down, and back up again.

As my fingertip re-traced its path down the pink ski run, this time starting to part them and gently push inside, she suddenly whispered “mmm ... no ... please...”

“What?! - you want me to stop?” I said, confused.