Perhaps the easiest people to fall in love with are those about whom we know nothing. Romances are never as pure as those we imagine during long train journeys, as we secretly contemplate a beautiful person who is gazing out of the window – a perfect love story interrupted only when the beloved looks back into the carriage and starts up a dull conversation about the excessive price of the on-board sandwiches with a neighbour or blows her nose aggressively into a handkerchief.