Hi Geoffrey, as I am sure you have found, there is nothing coming up on the web for a suitable towbar for your car, so truly out of stock. The diagram does not look overly different from the version that fits the XF, but it would need to be adjusted / fettled to suit your bolt pattern.
Probably best to work with a reputable towbar supply and fit company in your area, or alternatively make inquiries with the reputable Jaguar Breakers such as Eurojag and Auto Reserve - both can be found on the web.
N6 JMX