Mackies have a myriad of colours other than the stock colours shown on my website, and if they don't have the right colour in stock they make every effort to source the colour, for example a customer requested a kharki balmoral bonnet, sufficient material of the customers desired colour was sourced, so as to meet his demands, they still have enough material available to make a few more bonnets in that colour.
I suspect that the Dukes bonnet was originally lovat blue, but has faded over the years, when I see him or his wife next I will ask him.