It is my belief that this mixing of black and brown stems from Prince Philip. He took up carriage driving soon after his marriage to Her Majesty. The horses and carriages being then available to him. The vast majority of the Queen's horses are brown and the way of it is that brown horses have black (or very, very dark brown) manes and tails.

All competitors in carriage driving have livery colours for their grooms (1 sitting next to the driver and 2 hanging on at the back). If memory serves, there was some controversy at the time as to what livery colours Prince Philip could or should use. He couldn't use the Royal livery colours, so he had to opt for something else. Nor would it have been acceptable for him to use the Danish or the Greek Royal livery colours.

In the end the livery colours were chosen as Black and Brown - to match the horses. I have seen Prince Philip driving at the Championships at Sandringham, with his head groom and two hanging grooms wearing a mixture of brown and black. If I am remembering correctly all the browns were the same shade - not a mixture of tans and ox-blood and light and dark.

Regards

Chas