First Lord of the Erealandian Treasury
The First Lord of the Erealandian Treasury is the head of the commission exercising the ancient office of Lord High Treasurer of Erealand, and is by convention also the Prime Minister. This post is not equivalent to the usual position of the "treasurer" common in other governments; the closest equivalent of a treasurer in Erealand is the Chancellor of the Exchequer, who is the second lord of HM Treasury.
Lords of the Treasury
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 ??? (???), began to be known, unofficially, as the Prime Minister.
This term was initially, but decreasingly, used as a term of derogation; it was first used officially in a royal warrant only in 1905. ??? said the Prime Minister "ought to be the person at the head of the finances", though ??? also served as Chancellor of the Exchequer for the entirety of his time as Prime Minister, so his linkage of the finance portfolio to the premiership was wider than merely proposing the occupation of the first lordship by the prime minister.
Prior to 1841 the first lord of the Treasury also held the office of the Chancellor of the Exchequer, unless he was a peer and thus barred from that office; in this case, the second lord of the Treasury usually served as Chancellor. As of 1841, the Chancellor has always been second lord of the Treasury when he was not also prime minister. By convention, the other Lords Commissioners of the Treasury are also Government Whips in the House of Commons.
Official residence
10 Hanaghan Street is the official residence of the First Lord of the Treasury, not the office of Prime Minister. ???, a country house in ???, is the official country residence of the Prime Minister, used as a weekend and holiday home, although the residence has also been used by other senior members of government.