18th March 2003.
The last time Britain officially declared war was in January 1942 against Siam (Thailand).(1)
Ever since when British forces have operated under the Royal Prerogative mainly after ostensibly securing a UN Security Council Resolution, as with the 1991 First Gulf War when we drove Saddam Hussein from Kuwait.(2)
The 2003 invasion of Iraq was based on a perceived need for Regime Change hatched between Blair and Bush to remove Saddam Hussein without the clear and unequivocal backing as cited in the UN Article 1441. Even the British Attorney-General thought the legality was unclear.
The invasion of Iraq raised some nice Constitutional issues in that Blair’s Labour Government thought it wise to seek Parliamentary approval Today in 2003, one day before the invasion.
However this did not imply any ‘Prerogative Power’ being transferred.(3)
Back to the time when wars were ‘Declared’, as in 1914, Germany declared war at 11pm on 4th August (Berlin Time), and we responded likewise, at 11pm (British Standard Time).
Chamberlain on September 3rd 1939, announced a State of War at 11.15am (BST) with Germany, after it had not committed to withdrawal from Poland by 11.00am (BST).
Later the UK was to declare war on Finland, Hungary and Romania (later to change sides) on 5th December 1941.
In 1950 we went to war in Korea, after the Communist north invaded the south. This was termed an International Police Action, as under a UN Charter, war was outlawed, except when a country was under attack. What’s in a name?
1999 was the last time that the Queen refused the Royal Assent, but on the advice of the Labour Government, when Tam Dalyell brought under the Private Member’s ‘Ten Minute Rule’, an attempt to remove the Royal Prerogative to declare war, to Parliament.
(1) Siam had declared war on Britain and the USA.
(2) Under the Royal Prerogative Britain can declare war and deploy armed forces without a Parliamentary vote, though Cameron didn’t invade Libya in 2013 when he lost the vote.
(3) The Royal Prerogative came from the Constitutional Settlement of 1688 Bill of Rights, after James II had abdicated. This transferred to Ministers certain rights previously reserved for the Monarch.
Ref: guardian 23.8.2015. Martin Kettle.
Ref: waterlooregionww1.uwaterloo.ca/british-declaration-of-war-on Germany.
Ref: radioriel.org/the-great-war.Image Ref.