RAF Sealand was a former Royal Air Force

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 station in Flintshire

Flintshire

Flintshire is a county in north-east Wales. It borders Denbighshire, Wrexham and the English county of Cheshire. It is named after the historic county of Flintshire, which had notably different borders...

, north Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

 and operated between 1916 and 2006.

Under defence cuts announced in 2004 RAF Sealand was completely closed in April 2006. All remaining RAF units were moved to RAF Leeming

RAF Leeming

RAF Leeming is a Royal Air Force station in North Yorkshire, UK.HRH The Duchess of Cornwall is the Honorary Air Commodore of RAF Leeming. The Station Commander is Group Captain Anthony Innes....

. Part of the original airfield is now operated as the civilian MOD Sealand.
It was originally a civilian airfield and was taken over by the military in 1916 for training.