Turns out the new owner is a twit!
I needed to play around with a variety of settings to prove that theory.
In the end, it was playing around with the TV settings for Full, Justify, H-Fill etc that has me where I am now.
1024x768 setting on the Mini, and Full setting on the Panny, and I can see about 95% of the desktop. No other setting combination gets me a more complete view of the desktop.
Moving to install app for remote control so I can lose the usb mouse and keyboard next.
Getting there.