The first stage of the Refinery was brought on stream in October 1973 by Amoco (UK) Limited.
In 1975 the Refinery was expanded to a nominal capacity of 108,000 b/d of heavy Middle East crude.
The Refinery has undergone continuous improvement since the major 1981 upgrading, and is now capable of processing up to 112,000 b/d of light North Sea type crude oils. Other feedstocks can also be processed and the Refinery is now capable of a total processing rate of 118,000 b/d.