21St century

War in Afghanistan and Iraq, and terrorist attacks at home: In the 2001 General Election, the Labor Party won a second successive victory, though voter turnout dropped to the lowest level for more than 80 years. Later that year, the September 11th attacks in the United States led to American President George W. Bush launching the War on Terror, beginning with the invasion of Afghanistan aided by British troops in October 2001. Thereafter, with the US focus shifting to Iraq, Tony Blair convinced the Labor and Conservative MPs to vote in favor of supporting the 2003 invasion of Iraq, despite huge anti-war marches held in London and Glasgow. Forty-six thousand British troops, one-third of the total strength of the Army's land forces, were deployed to assist with the invasion of Iraq and thereafter British armed forces were responsible for security in southern Iraq. All British forces were withdrawn in 2010.

The Labor Party won the 2005 general election and a third consecutive term. Four Islamist home-grown terrorists plotted retaliation and on 7 July 2005, a series of four suicide bombings struck London, killing 52 commuters, in addition to the four bombers.

Nationalist government in Scotland: 2007 saw the first ever election victory for the pro-independence Scottish National Party (SNP) in the Scottish Parliament elections. They formed a minority government with plans to hold a referendum before 2011 to seek a mandate "to negotiate with the Government of the United Kingdom to achieve independence for Scotland." Most opinion polls show minority support for independence, although support varies depending on the nature of the question. The response of the unionist parties was to establish the Calman Commission to examine further devolution of powers, a position that had the support of the Prime Minister.

Responding to the findings of the review, the UK government announced on 25 November 2009, that new powers would be devolved to the Scottish Government, notably on how it can raise tax and carry out capital borrowing, and the running of Scottish Parliament elections. These proposals were detailed in a white paper setting out a new Scotland Bill, to become law before the 2015 Holyrood elections. The proposal was criticized by the UK parliament opposition parties for not proposing to implement any changes before the next general election. Scottish Constitution Minister Michael Russell criticized the white paper, calling it "flimsy" and stating that their proposed Referendum (Scotland) Bill, 2010, whose own white paper was to be published five days later, would be "more substantial". According to The Independent, the Calman Review white paper proposals fall short of what would normally be seen as requiring a referendum.

The 2011 election saw a decisive victory for the SNP which was able to form a majority government intent on delivering a referendum on independence. Within hours of the victory, Prime Minister David Cameron guaranteed that the UK government would not put any legal or political obstacles in the way of such a referendum. Some unionist politicians, including former Labor First Minister Henry McLeish, have responded to the situation by arguing that Scotland should be offered 'devo-max' as an alternative to independence, and First Minister Alex Salmond has signaled his willingness to include it on the referendum ballot paper.

The 2010 coalition government: The United Kingdom General Election of 6 May 2010 resulted in the first hung parliament since 1974, with the Conservative Party winning the largest number of seats, but falling short of the 326 seats required for an overall majority. Following this, the Conservatives and the Liberal Democrats agreed to form the first coalition government for the UK since the end of the Second World War, with David Cameron becoming Prime Minister and Nick Clegg Deputy Prime Minister.

Under the coalition government, British military aircraft participated in the UN-mandated intervention in the 2011 Libyan civil war, flying a total of 3,000 air sorties against forces loyal to the Libyan dictator Muammar Gaddafi between March and October 2011. 2011 also saw England suffer unprecedented rioting in its major cities in early August, killing five people and causing over £200 million worth of property damage.

In late October 2011, the Heads of Government of the Commonwealth of Nations voted to grant gender equality in the British royal succession, ending the male-preference primogeniture that was mandated by the 1701 Act of Settlement. The amendment also ended the ban on the monarch marrying a Catholic.