The Victorian Web gives details of his life before he became PM:
Perceval was educated at Harrow and Trinity , Cambridge, being awarded his College's Declamation Prize for English. He was awarded an MA in 1782 and was called to the Bar in 1786, practising on the Midland Circuit. He became Deputy Recorder of Northampton in 1790, the year in which he married Jane Spencer-Wilson in 1790: the couple had six sons and six daughters. Between 1794 and 1803, during the French Wars, Perceval was a member of the London and Westminster Light Horse Volunteers.
In 1796, Perceval became MP for Northampton, a seat which he held until his death in 1812. During his time as an MP, he held a number of government posts including that of Solicitor General (Jan 1801-April 1802), Attorney General (April 1802-February 1806) and Chancellor of the Exchequer (March 1807-May 1812).
Perceval was always a supporter of the government and this brought sinecures which kept him solvent until his legal career took off. He was the chief legal adviser to the Princess of Wales in the hearing of misconduct held in 1806; although she was found guilty of 'grossly indelicate conduct', Perceval was instrumental in arranging her reconciliation with George III. Always anti-Catholic, Spencer Perceval opposed Grenville's government's attempt to introduce concessions to Catholics in Ireland in 1807, thus contributing significantly to the fall of the ministry.Perceval was appointed prime minister in October 1809. History Today has an article about his murder less than two years later, written by Richard Cavendish:
In his book The Assassination of the Prime Minister David Hanrahan gives a vividly detailed account of that sunny Monday afternoon in May when at about a quarter past five the 49-year-old Spencer Perceval entered the lobby of the House of Commons on his way into the chamber. A man who had been sitting quietly by the fireplace stood up, walked towards the prime minister, took a pistol out of his overcoat and fired it at Perceval, hitting him in the chest. The prime minister staggered and fell, crying out ‘I am murdered!’
There were naturally moments of complete astonishment as the man who had fired the shot walked back to the fireplace and sat down again. He made no attempt to get away as an MP called William Smith (future grandfather of Florence Nightingale) and several others carried the stricken Perceval to the Speaker’s apartments, where they sat him on a table, holding him up. He said nothing more and uttered only a few sounds that Smith described as ‘convulsive sobs’. By the time a doctor arrived Perceval was dead. The pistol ball had struck him in the ribs.
In the lobby meanwhile the murderer was seized and his pistol was taken from him. It turned out that it had been hidden in a specially made pocket in his overcoat.Bellingham was publicly hanged a week later, though the evidence rather suggests that his insanity pleas should have been accepted. He was a businessman who had been falsely imprisoned for debt in Russia and was unable to get ministers to take up his case.
The Conservative MP for North West Norfolk, Henry Bellingham, is a direct descendant of John Bellingham. Henry lost his seat in 1997, partly because of the intervention of the UKIP candidate Roger Percival. Despite the different spelling of their names, he claimed to be a descendant of Spencer Perceval.