Heathrow taxis are always available because it's one of the busiest airports in the world, operating all day, every day. People come and go from destinations around the world and some of them are used to travelling prestigiously, however, many of the taxis at Heathrow are dull, to say the least. Royal Heathrow Taxis have a fleet of sophisticated cars with one special stipulation needed for each of them; they are ALL Mercedes. That is a necessity and it's one that has proved popular with clients from all walks of life.