its part of the mirror mate, mines done the same. take the mirror of, rub it down, bit of etch primer then satin black. good as new for a few quid compared to nearly 500 quid for a new one.

Hi mines an 04 vogue do you know if the mirror outer casing comes apart, its just that I'm looking to get it sprayed, easier to remove than covering the car ..

take no notice of my avatar, thats my old beast. mines a 54 with the same problem as yours, the plastic rear panel comes off seperate. probably easier to take the glass out to get it off without braking the clips, to get the glass off alter the angle so it points towards the ground then slide the glass up out of the mirror housing. if you got the time and patience you can take the whole mirror off the car the seperate the two halfs so you left with just the mount plate, you can get it sand blasted then powder coated for a perfect finish.