Stu, that colour is listed as being used on some of the early AC Ace/Aceca/Bristol cars, both UK and export, and clearly found its way onto some of the COB/COX cars as well. The car in the B&W pic, BEX 430 is listed as being originally painted Bright Blue Metalline with a cream interior. A visit to the site below will give you a large listing of AC cars that you can scroll through to find likely colour combinations which will in turn allow you to look up the actual car to try and track down a paint code.
http://www.acaceca.de.tl/AC-Ace-and-Aceca.htm
A few pics from the list of cars (serial #'s in the pic URL's) shows the likely colour to be a bit more blue than the magazine photo you posted. That photo; if you look at the road, the red shirt and even the greenery; appears to be over saturated with magenta, giving the car a more purplish hue.
That's the problem with choosing colours from the web or even photos - you are never 100% sure what it looks like until you see it in the flesh! Good luck.
