Conversations with some of my fellow passengers and general observance of others has brought me to document the rules of newspaper reading on the train.
So here goes:
1) If you do not have a newspaper, do not read the person opposite's. They have spent good money on it they want to have a nice new unread virginal newspaper. Not one that's been drawled over by you.
2) If you catch somone reading your newspaper, catch their eye and make them back off. (All unspoken obviously).
3) If the person opposite puts down their newspaper and they look as if they have finished with it, wait at least 20 mins and up to 30 depending on the individual concerned. During this period carry out thorough surveillance of the owner to see if they may be amenable to an approach for the paper.
Once this phase is complete, use the following expression: "Sorry, excuse me. May I read your newspaper?" The response will almost always be "Yes, no problem". To this you must respond "Thanks very much indeed".
Following this, revert to utter silence as you read their paper even though you are slightly annoyed that they have completed the crossword incorrectly.
4) If you have bought a multi-section newspaper, you are at risk of being approached by an undesirable group of travellers (and I mean you to read as much into that as you possibly can) who will approach you and ask to read one of the unread sections of the paper before you have had a chance even to breath.
This is unacceptable and such people should be dragged into the vestibule by their filthy matted locks and beaten with the newspaper until they are unconcious.
My thanks to "GuardianMan" who related the story from which I drew part 4. You know who you are.