1. Getting there (on an Express service) If you’re in a hurry to get to a London airport, expect to pay through the nose. With single fares from Paddington priced at £21.50 in economy class, the Heathrow Express is, pound-for-pound, Britain’s most expensive, above-ground, rail journey, clocking in at nearly £1.50 per mile. A return journey costs £35 – slightly …