On a recent journey, I was the only other passenger in First Class with a middle-aged woman sat a few seats away from me. Annoyingly, I had forgotten to bring my headphones on this journey. She was repeatedly listening to loud videos on her phone, so, after enduring it for about an hour, I - politely - asked her could she please stop doing so, which she agreed to. Ten minutes later, she started up again, so this time I wasn't quite so polite (although I didn't swear at her).
By this time, the crew and conductor had noticed - I'd already tipped the conductor off about her behaviour and he said he'd keep an eye on her, but hadn't bothered to do so.
Rather to my surprise, the crew told me - in no uncertain terms - to sit down, then struck up conversation with the woman, chatting away to her like a long-lost friend. Essentially this made it feel like it was me who was in the wrong and not her (although it did stop her from listening to any more videos).
As there was only one First Class carriage on the train, I didn't really have the option to move.
It rather ruined the rest of the journey for me.
Lesson learned - always make sure you have headphones with you for a long journey.