As of the beginning of the 17th century, the running of the Treasury was frequently entrusted to a commission, rather than to a single individual. Since 1714, it has permanently been in commission. The commissioners have always since that date been referred to as Lords Commissioners of the Treasury, and adopted ordinal numbers to describe their seniority. Eventually in the middle of the same century, the First Lord of the Treasury came to be seen as the natural head of the overall ministry running the country, and, as of the time of Robert Walpole (Whig), began to be known, unofficially, as the Prime Minister.