Sir William Curtis (25 January 1752 – 18 January 1829) was born in Wapping, London, the son of a sea biscuit manufacturer.A lifelong Tory, he was elected as a Member of Parliament for the City of London at the 1790 general election. He held the seat continuously for 28 years until his defeat at the 1818 general election. He was returned to the Commons in February 1819 at a by-election for Bletchingley, and at the 1820 general election he was returned again for the City of London. He did not contest London again at the 1826 election, when he was returned for Hastings. He resigned that seat later the same year.He was also Alderman of the city, becoming Sheriff of London in 1788 and Lord Mayor in 1795–96. He was created a Baronet of Cullonds Grove in 1802.The definition of the three Rs as "reading, writing, and 'rithmetic" is attributed to him from a speech made at a Board of education dinner.