The Jaguar XJ is a luxury sedan produced and introduced to the market by Jaguar in 1968. Between 1968 and 1985 the XJ was revised 3 times, designating itself as «Series I», «Series II» and «Series III».

The "Series III", of which this Sovereign is a part, was introduced in April 1979. It was available only in what was known as the "long-wheelbase" and incorporated a subtle "facelift" designed by Pininfarina.

Externally, the most obvious changes compared to the “Series II” were the thicker rubber bumpers and better incorporated in the bodywork, “flush” door handles, one-piece front door glazing, front grille with only vertical fins and new and larger rear lights incorporating reversing lights.