There are a number of categories of people who are disqualified from being members of the House of Commons:
• Holders of "offices of profit under the Crown", such as the Crown Steward and Bailiff of the Chiltern Hundreds - enabling the resignation of an MP;
• Non-British citizens, other than citizens of the Commonwealth and of the Republic of Ireland;
• People under the age of 21;
• People who have been detained under the Mental Health Act;
• Members of the House of Lords;
• Undischarged bankrupts;
• People convicted of treason;
• People who have been sentenced to more than one year in prison and are still serving that sentence at the time when they want to stand for Parliament;
• Those guilty of using corrupt practices at an election;
• Other public office holders - civil servants, members of the armed forces, the police, the judiciary - but not Justices of the Peace - diplomats, election officers and holders of other specified public positions.
Practising clergy and former Catholic priests used to be disqualified, but the Labour Government changed the law with the House of Commons (Removal of Clergy Disqualification Act) 2001.