The Peelites were a breakaway faction of the British Conservative Party, existing from 1846 to 1859, who joined with the Whigs and Radicals to form the Liberal Party ('Liberal' referring to their position on economic matters). They were called "Peelites" because they were initially led by Sir Robert Peel, who was the British Prime Minister and Conservative Party leader in 1846.
The Peelites were characterised by commitment to free trade and a managerial, almost technocratic, approach to government. Though they sought to maintain the principles of the Conservative Party, Peelites disagreed with the major wing of that party, the landed interest, on issues of trade; in particular, the issue of whether agricultural prices should be artificially kept high by tariffs. The Peelites were often called the "Liberal Conservatives", in contrast to "Protectionist Conservatives" led by Benjamin Disraeli and Edward Smith-Stanley, 14th Earl of Derby.
In 1845, facing a serious famine in Ireland, Peel sought to lower food prices by repealing the Corn Laws. He was able to carry the repeal vote in the House of Commons, but only at the price of splitting the Conservative Party; a split which led to the fall of Peel's government in June 1846, and its replacement by a Whig government led by Lord John Russell.
The leading members of the Peelite faction that developed after the 1846 split of the Conservative Party were:Sir Robert Peel
Sir James Graham
The Earl of Aberdeen
Lord Lincoln (later Duke of Newcastle)
Sir John Young
The Peelites numbered about a third of the old Conservative party following the 1847 general election. Their main political positions at that time were closer to the Protectionist Conservatives than to the Whigs and Radicals in parliament, except on the issue of Free Trade. The split had been so bitter on a personal level, though, with attacks on Peel by protectionist conservatives such as Lord George Bentinck and Benjamin Disraeli, that the Conservative Party was unable to reconcile the Peelites, even after the Conservatives officially abandoned protection in 1852.
After Peel's death in 1850, the Peelite faction (also sometimes referred to as the 'Liberal-Conservatives') was led by Sir James Graham and Lord Aberdeen, the latter of whom became prime minister in 1852 by forming a government in coalition with the Whigs. This government fell in 1855 as a result of the unpopularity of its hesitant attitude during the Crimean War.
After the fall of the Aberdeen government, the Peelite faction took most of the blame for their management of the war in the Crimea. The party further lost cohesion with some members including Gladstone, Graham and Herbert accepted cabinet posts in the new government led by Viscount Palmerston only to resign a few weeks later when the Government agreed to hold a commission on the conduct of the recent war. Others stayed in including George Douglas Campbell, 8th Duke of Argyll and Stratford Canning after which the Peelites with now no agreed overall leader appeared to be a band of independents rather than a political faction. In the 1857 election their numbers further decreased to around 26 (or maybe less than 20 - identifying who was and who was not a Peelite became increasingly difficult) .
The Peelites finally disappeared as a distinctive political faction when they agreed to combine with the Whigs, Radicals and Independent Irish Party MPs to bring down the Conservative government of the Earl of Derby in 1859. The subsequent creation of Lord Palmerston's ministry out of this combination was the birth of the British Liberal Party. Several leading Peelites (including Gladstone, Herbert, Cardwell, and Newcastle, but notably not Graham, who was one of the driving forces behind the coalition) accepted cabinet posts in this ministry, though some Peelites became independents or returned to the Conservatives.
However, after their 1874 victory the Cons did not ever try to bring back the Corn Laws, becoming de facto Peelites themselves.