I have a 2015 XJL Portfolio AWD. I looked in the owner's manual for reference to heated outside mirrors and found no mention. I find it hard to believe that a car this luxurious and designed for use in England would not have this feature.

 

I believe they work in conjunction with the rear defroster. Once you turn that on, the heated mirrors automatically turn on.

Do your mirrors have the little heated-mirror symbol on them?

 

There is no symbol on mine (which are heated), but US-spec mirrors are very different to UK ones as you seem to have curves and writing on them. They should work as Hank describes.

If you want to check yours just pull the look to see if there are two wires attached to the rear of the glass with metal tab crimps. Push the glass in towards the car until fully adjusted inwards and look behind the exposed outer edge. You don't need to remove the glass to see as they are along the outer edge (maybe 1" in).

 

Thanks for the help guys. I will check them out as per the guidance.