The Leader of the House of Lords is a cabinet level position in the British government, responsible primarily for monitoring the ruling party's business in the House of Lords. Traditionally, the Leader of the House has also acted as a parliamentarian who advises the House on matters of procedure and order and calls attention to any breaches of the same.
Evidence of the position's formal existence dates to the early eighteenth century, when it was typically held by one of the Secretaries of State (there were two at the time) who was also a peer. Throughout the nineteenth and early twentieth centuries, the position was formalized and frequently held alongside a department-level portfolio (oftentimes one of the more influential ones). In periods of coalition governance, it was not unheard of for the party leader who was not Prime Minister to adopt the position as his own.
As the House of Lords has declined in power, the position of Leader of the House has arguably done the same. The last Leader of the House to hold a department-level portfolio was in 1966. Since then, the Leader of the House has typically held a second title within the Privy Council instead. Recent proposals on reforming the House of Lords have suggested that the Leader of the House's parliamentary duties should be absorbed by the Lord Chancellor, though the position's importance as an instrument of the ruling party would remain. | 
