The cheapest flight to London Heathrow you can get by boooking just before departure.
The most popular airlines on the route Madrid Barajas - London Heathrow: Iberia (IB), Alitalia (AZ), TAP Air Portugal (TP).
Direct flights last about 2h 18min.
Direct flights available 7 days a week.
Direct flights: Iberia (IB), British Airways (BA).