I used to travel from Glasgow to London every other week and would choose the quiet carriage in first class.
One one occasion sitting before we departed a cockney was talking in his phone in a loud way.
As the train set off he kept talking and laughing, I knew this was a situation I could not endure so I got out if my seat, tapped him in the shoulder and said.
Sorry to interrupt mate but I booked this carriage to avoid having to listen to people's conversations. There is no way I can listen to you all the way to London. No offence but you need to either stop or move to a carriage that allows it.
He left.
A old woman smiled at me and thanked me for getting rid of the guy.
I feel these types of a situations need to be dealt with immediately, or sooner.