Well would you bloody believe it
Laid under the car thinking what am I doing here, looked up and saw what seemed to be a false bottom just behind the rear firewall
Okay - made a mess of the boot lining searching for it, but hey presto found it.
Sooooo nice to look at the calipers from the top.
Oihhh Les - found that vertical come horizontal bolt.
Now to get on with the work in hand.
Thanks Les and Jason for your help.
Moral of the day -
"If you have rear inboards make sure you have a false bottom"
The previous owner was a Jag fanatic so obviously realised the problem regards access.