The Conservative Party can claim to be the oldest political party in Europe, with a long commitment to private property and free enterprise.
Michael Howard has led the Tories since 2003
In the 17th Century, the party's predecessors - the Tories - backed the power of the Crown, believing it to be a check on Parliament and the interests of their political opponents, the Whigs.
Support for the Monarchy remains a fundamental belief for Conservatives.
The Whigs dominated 18th Century parliaments until William Pitt the Younger became prime minister in 1783.
His support for free trade and sound finances laid the foundations of modern Conservatism. Opposition to state interference in private enterprise became one of the party's core beliefs.
In 1830, the description "conservative" was first used to label this political movement, although the term "Tory" - from the Irish Gaelic word for "bandit" or "outlaw" - has remained in common use to this day.
In the middle of the 19th Century, Conservatives were split over the decision by their prime minister, Sir Robert Peel, to abolish the Corn Laws, which had maintained the price of food at an artificially high level.
On one side were those who believed in free trade; on the other, those who wanted to protect agricultural interests.
Conservative and Unionist
Under the leadership of Benjamin Disraeli, Tory wounds were healed and the party united in support of an agenda that would strengthen Britain's position in the world, while offering improvements in conditions for the less well off.
In 1886, the Liberal Party split over the issue of home rule for Ireland, and the Liberal Unionist Party was formed. It formed an alliance with the Tories before being formally absorbed in 1912, creating the full title of the present-day organisation: the Conservative and Unionist Party.
Conservatives had resisted moves to grant home rule to Ireland, fearing it would lead to the break up of the United Kingdom. The party retains a strong commitment to Northern Ireland being a part of the Union with Britain.
Although associated with landowners and the aristocracy, and more recently the middle classes, the party has looked for support across social boundaries.
Chamberlain failed to stand up to Hitler
After the extension of the franchise in the 20th Century, working class votes became increasingly important to secure victory at the polls.
In the 1930s, Conservative prime ministers faced crises at home and abroad.
For Stanley Baldwin, it was the abdication of Edward VIII, who renounced the throne for the American divorcee Wallis Simpson. For Neville Chamberlain it was the rise of Adolf Hitler, and the disastrous policy of trying to appease the Nazi dictator.
When "peace in our time" turned into all-out war, Winston Churchill emerged as the man to lead the Conservatives, and the country, out of the abyss.
As head of an all-party government, he epitomised Britain's determination never to surrender, and became revered as one of the Tories' greatest leaders.
This made it all the more shocking for the Conservatives to see Labour elected by a landslide at the election of 1945, but after the hardships of the 1930s, the country was demanding social change.
By 1951 the Tories, still led by Churchill, were back in power. A period of prosperity helped to keep Labour in opposition for 13 years.
Supermac to Maggie
Prime Minister Harold Macmillan, who took over in 1957, famously told voters: "You've never had it so good."
But by 1964, the country was in recession, and the Tories had been damaged by the Profumo scandal. Britain was in the midst of Beatlemania, and Merseyside MP and Labour leader Harold Wilson became prime minister during the Swinging Sixties.
Edward Heath restored Tory fortunes in 1970, but his election victory was followed by conflict over the Industrial Relations Act and an international economic crisis triggered by sharp rises in the price of oil.
Ted Heath won a surprise victory in 1970
Labour returned to power in the two elections of 1974, and by the time of the next election the Conservatives had a new leader.
The election of Margaret Thatcher as Britain's first woman prime minister in 1979 was to be the start of an extraordinary period of electoral success for the Tories.
At home she took on the trade unions and began privatising many nationalised industries. The miners' strike became an emblem of the bitter divisions within Britain, but abroad, her stature grew.
The successful campaign to expel Argentine forces from the Falklands, and her "handbagging" of various European leaders, helped to forge her image as the Iron Lady.
The Major years
In the end it was the enemies within who removed her from office.
A leadership challenge by Michael Heseltine opened the way for John Major to be elected in her place.
Margaret Thatcher won three consecutive general elections
As prime minister, he secured concessions for Britain in Europe, and took the country into the Gulf War. He called an election in 1992, and narrowly won the Tories their fourth victory in a row.
Back in Downing Street, Mr Major found himself leading a party increasingly divided over Britain's place in Europe. In 1994, eight "Eurosceptic" Tory MPs defied the party whip and abstained on a key vote in the Commons.
The following year, Mr Major resigned the leadership, telling opponents within the party to "put up or shut up". He won the leadership election, but the bitterness remained.
In a remark intended to be private, Mr Major had referred to Eurosceptics within his Cabinet as "bastards".
The Conservatives were now in the grip of "sleaze". As Mr Major launched a "back to basics" campaign, the newspapers carried embarrassing revelations about a string of Tory backbenchers and ministers, whose private lives did not accord with the party's moral values.
Others were forced to resign over a "cash for questions" row.
When the election came in 1997, the Conservatives went down in a crushing defeat.
In the leadership election that followed, William Hague beat Kenneth Clarke in the third round of voting.
Mr Duncan Smith's run as leader was cut short by fellow Tory MPs
The party did well at the European elections in 1999, but opinion polls continued to show the party trailing Labour and sure enough Mr Hague hardly made any in-roads into Tony Blair's majority.
Like Mr Major, Mr Hague quit immediately clearing the way for a leadership battle that ran throughout the summer of 2001 and eventually saw Iain Duncan Smith taking the top Tory job beating the likes of Ken Clarke.
In the Commons Mr Duncan Smith failed to score against Mr Blair, and his conference speeches are likely to go down in history for all the wrong reasons.
Shortly after he told the Tory conference in 2003 that the "quiet man is here to stay and he's turning up the volume", Mr Duncan Smith was out, toppled by fellow Tory MPs, and Michael Howard was crowned party leader.
Since then the Conservatives have seemed in more optimistic mood but it remains to be seen if their renewed confidence translates into more seats in the Commons.