There is a switch inside the center console. I do not have a manual to check into.
I'm sure someone will have a quick answer for me.
It is a 2007 XK. I have attached a pic with this post. what is it for, and what does it control/do?

 

Surley this is aftermarket, so your best bet is to trace where wires go...

 

Agreed, no switch in my 2007 XK's console.

 

+1

My 2007 didn't have one of those.

It's a neat installation for a PO or aftermarket addition. Possibly an isolator for some function e.g. electric aerial? As suggested above, trace the wiring.

Graham

 

Antenna power?

 

If only it were a "TMPS Warning Message Disabler" :P

 

I fitted a switch there in my '07 to control the exhaust valve by wiring it across fuse 19. The car was a bit loud after I fitted highflow cats so it was good to be able to quieten it down when I wanted to.

 

...aftermarket radar detector? And the owner removed the detector but left the switch?

 

It's the hidden actuator switch for this accessory that was installed by Q Branch. Curiosity seekers think it's not real when they push the button and nothing happens.