Bob,
As I wrote in my previous posts, the four colour scheme was used in Canada and Germany from about 1962 to 1969. This was used on the Mk.5, Mk.5 LR, and the Mk.11LR.
The three colour scheme was used only in Germany from 1970-1975. This was used only on Mk.11LR versions.
Don't expect any paints out of the jar to be a colour match. For my four colour Centurion Mk.11LR I had to mix a variety of Tamiya and Model Master Acrylic colours to get an accurate match to the colour plates. On the real tanks these paints faded very quickly and were touched up by crews or completely repainted by hand resuitling in a semi-hard edge cam pattern.
Here are the paints I used, I did not keep track of the ratios:
Tan-Model Master Acryl Sand FS 33531 and Radome Tan
Green-Model Master Acryl Panzer Olivgrun 1943 and Dunkelgrun RLM 71
Brown-Tamiya Red Brown XF-64
Grey-Model Master Acryl Camouflage Gray FS 36622
For the three colour cam I picked up a couple of the old Testor Corporation 1/4 Oz. bottles of Flat Olive Drab #1165 and Flat OD Green #1164...these Enamel colours look very close to me from memory to the two greens used in the three colour cam as used on the Centurions, M113s, AVGPs, Iltis, etc...I will be mixing some Tamiya paints or Model Master Acrylics to match the enamel colours. I will be using Tamiya NATO black and a touch of grey for the black.
These PDF files should answer your pattern and colour questions.
http://www.armouredacorn.com/Reference/ArmourColours/Centurion%204-Colour.pdf http://www.armouredacorn.com/Reference/ArmourColours/Centurion%20NATO.pdf