The Heathrow Express is not free for most adults, but in 2026, it offers several complimentary options for specific groups. Children aged 15 and under travel for free at all times when accompanied by a paying adult, making it a favorite for families. For adults, a standard one-way fare starts around £25, or as low as £5.50 if booked at least 90 days in advance. There are also "complimentary upgrade" programs: if you hold a British Airways Gold Guest List, JetBlue Mosaic, or Star Alliance Gold card, you can purchase a standard ticket and receive a free upgrade to "Business First Class" by showing your status to the onboard staff. It is important to distinguish the Express from the Elizabeth Line, which is cheaper (around £13) but slower, and the free "inter-terminal" shuttles; travel between Heathrow terminals 2, 3, 4, and 5 is free for everyone, but any journey into Central London (Paddington) requires a paid ticket or a valid contactless payment.