As a friend of mine ponders whether to buy one or not, I find my mind drawn to one of the most extraordinary Jaguars ever made. And no, it’s not an E-type, or an XK120, nor even a Mk2. It’s an X350 XJR. And now I can almost hear you trying to place it. Fret not, it’s a process even I have to go through, and I’m meant to do this for a living.