Thanks for your responses,
I have had a go with the Scale Object Texture, varying it from 0.002 up to 20 but it had no effect. I don't think it can be the lighting as I have done nothing with the lighting and the colour does change a little when the texture is changed.
I'm not really sure what you mean about a UV mapped object but if you mean have I used Scale Object Texture, then yes.
Here is a link to the program which I am trying to get this to work in with all textures included so that you can run it. The idea is that you can select a skin colour and the cat will change its fur colour.
Any help you can offer would be greatly appreciated.
Lucas Tiridath