Fawley over the last few years has realigned itself for low sulphur gasoil/Diesel market as demand increases and demand for Petrol has decreased. To achieve this various modifcations have been made to the plant, the demand for crude has deceased hence less crude imports now. The different types of crude may be because of this.
The Russian crude loaded in Primorsk is very sour and expensive to extract the sulphur and the north sea crude sea is generally quite light,good quality, but expensive and not the best for making diesel.
One of the reasons Fawley seems to be getting the crude from Middle East is it is quite good for Gasoil and cheap, it comes from Exxon fields. Normally part discharges in other Esso refineries in Le Harve, Rotterdam before it gets to Fawley.