OK, so quick update for anyone considering a wheel colour change, I contacted Auto Curators in Hook who said they wouldn't just paint the wheels as it would obviously take up valuable garage storage space, but did put me onto the outfit they use called My Alloys near Basingstoke. Very nice people to deal with and talked me through their process (they powder coat not wet paint) and then gave me the quote £406.00 for all four wheels, there was a slight scrape on one wheel but otherwise they were in fairly good condition so that price might change if there was more corrective work to be done. Anyway I went ahead with the work and picked the car up yesterday, very pleased with the outcome going from diamond cut to gloss black as I have the black pack on the car it kind of made sense. So, great job, nice to deal with and a good price, couldn't be happier! Definitely recommend!