LairdScooby

Punctual

Concentrate

Enhancing

Basil

Paint

Walk

I also have an iCarsoft JLR code reader - all good with it so far but it has spent most of its time with me in my Honda CR-V due to a recurring knock sensor fault which has turned out to be something else.

Welcome aboard Adrian, lovely looking XKR there, first i think i've seen in white.

Best way is to check the flow using a garden hose. On any engine i prefer to remove the thermostat and refit the housing then remove the top hose from the rad and insert the garden hose into the top hose - usually a snug fit and then turn the hose on. This runs clean water backwards through the system, exiting from the rad top hose stub so gives a good reverse flush of the system. As a simple go/no-go test to see if it's blocked, run the engine up to temperature and once the 'stat opens, the top hose should be hot. Switch the engine off and use the palm of your hand to feel the temperature of the rad going from top to bottom. It should have a gradual reduction in temp as you get closer to the bottom hose, any sharp changes indicate there is probably a blockage around that place on the inside.

Promenade

The other thing to check is whether the radiator is blocked as that sounds very likely. Also check the condition and security of the cooling fins in the rad, if any are missing this will compromise the cooling, even at idle in the driveway. Also worth confirming the correct antifreeze has been used in the past as per what N6JMX points out.

Hokey-Cokey

Pulling

Cream

Alien