Master of the Royal Mint
The full tale of what happened to him as Master of the Ankh-Morpork Mint and Deputy Chairman of the Royal Bank of Ankh-Morpork (ie, the one who takes the Chairman for walkies) is told in Making Money.
The position dates back hundreds of years, when it would be given by the ruler of Ankh-Morpork to his drinking pal. The mint would then be used as an overly elaborate money-box, with the Master turning up every now and then with a big sack, a bad hangover and a meaningful look. Eventually, people realised that someone should be present who knew what was going on and was (mostly) sober, and so the position of foreman was also instituted, a position of which Mr. Shady the Eighteenth is the latest incumbent.