Something similar happened to me on the silverlink about 4 years ago. I used to get it to work, the journey was an hour, and i always used to use that hour to sleep, listening to my cd player. Only way to survive the silverlink!

Once, i woke up feeling something on my bum, at first, a bit groggy, i thought it was something in my back pocket, then i realised the guy next to me had got his hand under my arse and was having a damn got squeeze.

I leapt up, said to the whole tube at large,"this pervert was touching my up while i slept." and hit him very hard over the head with my cd player.

Then i just moved carriages, and everyone else just stared at him while he looked like he wanted to just disappear...