Heathrow Terminals 1,2,3 Tube Station was originally called the Heathrow Central Tube Station when it opened in 1977. It was renamed to the present name in 1986, when Heathrow Terminal 4 Tube Station opened.
At Heathrow Terminals 1,2,3 Tube Station, you can take the Piccadilly Line trains to Heathrow Terminal 5 Tube Station but not to Heathrow Terminal 4 Tube Station, and the line from Terminal 4 to Terminals 1,2,3 is unidirectional. If you need to go to Terminal 4 from Terminals 1,2,3, you need to take the Heathrow Connect train. To go to Terminal 5, you can use the Piccadilly Line or take the Heathrow Express. The difference between the two is services between terminals on Heathrow Connect and Heathrow Express is free whereas on the Piccadilly Line you need to pay.
Platform level at Heathrow Airport Terminal 1,2,3 Station (GPS: 51.47205, -0.45462) Source: https://commons.wikimedia.org/wiki/File:Platform level at Heathrow_Terminals_123_outside.JPG Author: Sunil060902