This weekend is probably the most macabre weekend of the year. Halloween will fill London with ghouls and poltergeist on Friday, Day of the Dead festivities will lure deceased souls from the afterlife on Saturday and early Bonfire Night fireworks displays will celebrate the gruesome executions of Guy Fawkes and his conspirators 420 years ago on Sunday. All that is to say, London's public transport will be particularly in demand over the next few days.