I presume you have a self dimming mirror? You can get a cheap ish replacement by following the info below.
Up to about March of 2008, the US Distributor in Holland MI, Magna Donnelly, was supplying replacements for free because of a recall. (The fluid is toxic) Replacements cost nearly $400 from Jaguar as an OEM item. So this what quite a deal indeed. The last free replacement occurred on or about October 2008. Since then, replacement mirrors are obtained through a vendor, Sybesma's Electronics, at a cost of $75.
Calling Magna Donnelly number (616-786-5115) will result in a recorded announcement saying if you are calling about a replacement interior mirror, you should contact Sybesma's Electronics. They are a contract vendor handling the mirror replacement on behalf of Magna Donnelly.
I emailed Sybesma's Electronics and received a reply from "Stacy" <orders@sybesmas.com>. she sent a PDF form with instructions to return along with pics of the mirror and its mounting point. They also require info regarding the connector, its color, the number of pins and the color of the mirror wires.
The firm remanufacturers these units, and they will ask for your old mirror as a core. The rebuilt mirror uses a gel pack instead of the toxic fluid so at least the potential damage issue is eliminated. The cost used to be $75, but around 2010 it went up to $95.
Once they receive the mirror data, if they can, they pull one from stock, or manufacturer yours to spec, and upon payment ships it out. You use the shipping box to return your old mirror. Keep in mind you need to remove your mirror in order to photograph the pedestal attachment point. It is not difficult, but if done incorrectly may crack the windshield.
The mirror on my ā97 XK8 was attached to the windshield by a parallel slide joint using a plastic detent button. Bonded onto the inner windshield is a metal clip that accepts the pedestal mount. The mirror is removed by sliding it downward off the mount.
Hope this helps