Walking towards the station this evening I noticed a young lady with a vey short satin texture skirt in front of me. She had a rucksack on which was causing her skirt to rise up at the back as she walked. I saw her pulling the skirt down. Intrigued I got right behind her and wonder of wonders as she walked her skirt rode right up exposing the enticing darker tops of her tight , the cheeks of her bottom and her white knickers. I followed her for 15 minutes and this pattern of the skirt riding up exposing her knickers and her pulling it down repeated itself a number of times. I was getting more and more aroused as we approached the station. It was the final straw on the station steps. I saw a hole in the gusset of her tights exposing the top of her right thigh and part of her white panty gusset. I could take no more . I spurted into my pants and had to find the station toilet quickly to clean myself up.