From 7 January 2005 until 17 September 2006, the loop via Heathrow Terminal 4 was closed to allow the connection of a spur line to the now operational Heathrow Terminal 5 station.
Fra 7. januar 2005 til 17. september 2006 var loopet via Heathrow Terminal 4 lukket for at tillade tilknytningen af en stikbane til den nye Heathrow Terminal 5 Station.