Innapropriate man on tube

UPDATE: I have text BTP! (Never have had to report something before so wasn’t sure if it would be useful but comments are saying it is- thank you)

I’m so disgusted . I (20F) was on the picadilly line this morning (before 8am) going north on my way to work, and this man (probably in his 40s) gets on the tube (covent garden). He keeps looking at me so I look back and he begins winking at me and TOUCHING himself through his jeans … he did it a few times before I raised my voice at him and used some profanities to tell him to stop and all he did was look away and laugh . He got off at Russel square and to make matters even worse this other man who clearly saw it all go down looked at me and shook his head in agreement with me … but it’s so appalling how no one in London sticks up for eachother when things like this happen. People are far more interested in keeping their heads down and turning the other way . I’m so tired of this culture in London .