The unreformed House of Commons is a name given to the House of Commons of Great Britain and (after 1800) the House of Commons of the United Kingdom before it was reformed by the Reform Act 1832.
Until the Act of Union of 1707, which united the Kingdoms of Scotland and England to form Great Britain, Scotland had its own Parliament, and the term can be used to refer to the House of Commons of England (which included representatives from Wales from the 16th century). From 1707 to 1801 the term refers to the House of Commons of Great Britain. Until the Act of Union of 1801 joining the Kingdom of Ireland to Great Britain (to form the United Kingdom of Great Britain and Ireland), Ireland also had its own Parliament. From 1801 to 1832, therefore, the term refers to the House of Commons of the United Kingdom.
In medieval political theory it was believed that sovereignty flowed from God, not from the people, and that monarchy was the form of government ordained by God. The King (or Queen) was "the Lord's anointed," and it was the duty of the people to obey the King as God's representative. The King had a corresponding duty to rule for the people's benefit, and from an early date it was accepted that this included the duty to listen to the advice of the people, as expressed by their chosen representatives. To this idea was added the practical consideration that it was easier for the King to collect the taxes he needed if the people consented to pay them.