1921 Site first developed by the Atlantic Gulf and West Indies Petroleum Company (AGWI). 1925 AGWI purchased by Standard Oil - whose initials gave Esso its name: SO spells Esso ! 1951 The new refinery opened by Prime Minister Clement Attlee. Esso Petroleum formed. 1958 First chemicals project began. 1966 Esso Chemical (later to become Exxon Chemical, then ExxonMobil Chemical) began operations. 1969 Marine Terminal extended - to one mile in length. 1986 Esso became the first UK company to introduce unleaded petrol. 1988 Computerisation of all control rooms. 1999 Merger of Exxon and Mobil to form ExxonMobil. 2001 50th Anniversary of the "new" refinery.