We travelled down to London on the train. Quite an entertaining journey thanks to the lady (?) who objected to being asked to turn off her mobile phone as she was in the Quiet Zone. Much muttering, glaring, reports to the train manager ….. We then caught the tube to Heathrow and can recommend the little shop just past the platform for snacks etc. Much cheaper than at the terminal! Check-in etc went smoothly so off we went to explore the shops......