A couple of weeks ago I saw an old guy, maybe 60 or so, blatantly reading the smartphone of the young lady next to him as she held it up to her face. She gave no sign of detecting him but it was obvious enough for me to notice, sitting almost opposite and facing their way. He then started staring down at her legs - she had a fairly short pair of shorts on. After 4 or 5 stations of this - alternating his stare between her phone and her legs - he shifted to the priority seat immediately in front of his former one, so that he should now face me, exactly opposite, but instead he turned to stare back down the carriage, past the young lady. Then he stared down at her legs again. Then he leaned in towards her so that his head was almost over her knees and stared up between her legs. At this she quickly pulled her phone away from her face, lowered her head a little to get closer to his level, and gave him daggers for a couple of seconds, forcing him to withdraw from her space and, finally, look my way, although he avoided looking at me. I was staring at him with my mouth open in shock, wondering what to do, when he suddenly stood up and walked quickly away up the carriage. The lady shot a glance around - whether to see if anyone else had noticed or simply to check for other perverts, I have no idea - and then smartly resumed her addiction.