I have a Jaguar Xk8 1999, but the Parking brake seems to be stuck on
and this is further confirmed with the parking light shown on the
dashboard. The 1999 XK8 uses a cable type of Parking brake, where you
use the same lever to put the brake on and off, however the lever is
completely loose, almpst as though the cable cas snapped, but if that
were the case then the brakes should of let go and the light would of
gone out from the dash. The car does behave as if the parking brakes
are on, so how do I release the parking brake if the lever does not
work ?

Driving with the parking brake set at "on" can cause serious problems
to your brakes. I think its time to take your car to a mechanice. I
had the same problem about a year ago, and they had to install a new
cable in order for the parking brake to go down.

Steph53