By Ben Selby Any Jaguar XK120 is special. Built from 1948 to 1954, the XK120 was the car which made Jaguar as we know it today. With its XK straight six and gorgeous flowing lines, the XK120 quickly became the must-have accessory for all tycoons and celebrities, such as Clark Gable and Frank Sinatra. The XK120 also saw its fair …