Middlesex is one of the 39 historic counties of England and the second smallest by area. The low-lying county contained the wealthy and politically independent City of London on its southern boundary and was dominated by it from a very early time. When county councils were initially introduced in England in 1889 around 20% of the area of Middlesex, and a third of its population, was transferred to the County of London, and the remainder formed a smaller county, in the north west, under the control of Middlesex County Council.

Despite the disappearance of the county, Middlesex is still used informally as an area name and was retained as a postal county; which is now an optional component of postal addresses

ENFIELD • EDGWARE • HARROW • NORTHWOOD • PINNER • RUISLIP • STANMORE • WEMBLEY • ASHFORD • BRENTFORD • FELTHAM • HAMPTON • HOUNSLOW • ISLEWORTH • SHEPPERTON • STAINES • SUNBURY-ON-THAMES • TEDDINGTON • TWICKENHAM • GREENFORD • HAYES • NORTHOLT • SOUTHALL • UXBRIDGE • WEST DRAYTON

London Heathrow Airport or Heathrow (IATA: LHR, ICAO: EGLL), located near to London, is the largest and busiest airport in the United Kingdom. It is the world's third busiest airport for passenger traffic and it handles the most international passenger traffic in the world. Heathrow is owned and operated by BAA, which also owns and operates six other UK airports. Heathrow is the primary hub of British Airways, BMI and Virgin Atlantic.