Train of Thought Derailment

I love trains - I've said so before - how wonderfully fruitful a peaceful stretch of writing time train travel can provide. But sometimes I really hate being stuck on a train. When the amply endowed lady sits beside (and partially on) me. The one with nothing to read. The one who is going to bludgeon me with chat, all complaints and cliches, till my ears bleed. Oh please, no, oh no ...

Lady (after sighing pointedly a number of times, which I ignore, trying to quell my growing dread): I always eat on trains - it's because I get so bored.
Me: Ah? I always bring work to do on trains. (wave sheaf of papers, smile politely, try to go back to work.)
Lady: (randomly) You can't trust computers ... (long story follows about how she thinks somebody stole her bank details from a computer once and now she only pays cash for everything)
Me: Ah? (return to paragraph and re-read it AGAIN desperately trying to concentrate)
Lady: And nobody gives their seats up for old people any more. Except on buses. Young men on buses. They stand up. (long story follows about the way young girls don't stand up. Though perhaps on buses they do.)
Me: Ah. Oh.
Lady: (suspiciously) Is that work you're doing?
Me: (hopeful that the penny has dropped) Yes! Yes, I'm working.
Lady: What do you do?
Me: (stupidly) I'm a writer.
Lady: Jilly Cooper's a writer. I don't know where she gets her ideas.
Me: (in the spirit of grasping nettles) I don't have so much trouble with ideas. More with having enough time to get the writing done. That's why I always work on trains. (Hopeful smile - wave paper - resolutely make meaningless mark in the margin to look as if I am, indeed, at work)
Lady: I don't know where you get your ideas. What did you say your name was? I've never heard of you. Have you ever been to Ireland? I was going to Ireland on a holiday but they wanted to get money from me off a computer, so I'm going on a bus.
Me: (thinks) I wish I'd gone on a bus ...

I would pay good money - by computer or in cash - for a cloak of invisibily and a cone of silence. To use on trains. Please, please, could somebody invent them soon?