The seeds for this encounter were sewed over a year ago. I'd met a sub woman via a dating site. A statuesque woman around 40. A firm size 12 with powerful thighs and huge tits. Seriously sub with a playroom built in her garden and a love for fisting. We met a handful of times but her car crash of a life bought things to an unhappy ending. I'm near Bournemouth and she's east of Southampton so it was unlikely our paths would cross again. Fast forward to this summer and I'm filling up at a service station....yes you've guessed it, as I go in to pay, she is coming out. Still looking hot, wearing a tight top and tight skirt which showed her magnificent arse at its best. Her killer heels just screaming fuck me. I recognised her instantly but she didn't notice me. However once I'd paid and was walking back to my car....she was waiting for me. Whilst a little awkward, it was pleasant. We spoke about our children, work, etc. The usual stuff. Out of the blue she said "will you fist me please?" I nodded and asked her "just say where and when." "Here and now" she came back with. We swung back to the car park, parked up and she led me to a pedestrian tunnel under the m27....connecting the West and east bound service stations. I never knew it was there but clearly she'd used it before. Weirdly no words were exchanged between us but once half way along the tunnel, she simply leaned forward against the tunnel wall, opened her legs, pulled up her skirt and braced herself. Her cunt was soaked and open. Wiping my hand on her dripping pussy and it was lubed. My four fingers hardly touched the sides. She was much slacker than I'd remembered. Two years of what I guessed was constant fisting had stretched her cunt a lot. Effortlessly my whole hand slipped into her. Even with a clenched fist it was easy to enter her. She was so wet, her juices now running along my arm and down her thighs as she started cumming. "Both hands" she hissed. It was tight but both hands together now started fuckin her cunt, I quickened the pace and at one point lifted her off the ground. Throughout she covered her mouth to keep quiet and I lost count of how many times she came before her legs gave way and she slumped to the ground. "I needed that" she said, "thanks." That was it. She got up, adjusted her clothes and started walking back towards the car. "What about me" I called after her. "Next time" she called back. I followed her back to the cars, licking her juices off my hands. She had gone by the time I got back to my car but last night messaged your turn now. I can't wait!