Translating JTIS into English...

If its the rear ARB drop link (JTIS calls it a stabilizer bar link no7 on the pic in JTIS of the rear suspension) for sale here

JAGUAR X TYPE REAR ANTI ROLL BAR DROP LINKS C2S45009 | eBay

Thanks Buck.

The "knocking" souns more like a driveshaft issue to me... would you agree, or could these be part of the problem?

Probably means these
CONTROL ARM

One of mine went and fooked the rear tyres
http://www.jaguarforum.co.uk/f26/back-end-tyre-trouble-45793.html

Goudy's links should help, but you can get them for 35quid on Ebay from Jaguar dealers Ebay shops. It is most likely the control arm. If you jack up and hold the wheel at 12 n 6 o clock, and rock it, the inner bush on the control arm normally wears first. Just replaced mine weeks ago. It is only 2 bolts, but geez they were tight.
I would suggest changing the ARB links and bushes, these wear quickly, are cheap and easy to replace.

Goudy, I had a similar tyre nightmare, my tyre stripped the first 2 inner inches off my tread for no reason. I put it down to a bad Pirelli tyre. But I did research tyre fitters/suppliers in the area of France I was visiting, so I knew where to get similar deals as the UK.