As a mixed raced woman unfortunately which ever term you use will inevitably offend someone, it's more the context, the way it is said and the reasoning behind it been said. Over the years I've been referred to as been black, brown, coloured, mixed race, tanned, half-cast, well done and a few others I won't repeat but I'm sure you can imagine. I would never use 'half-cast' in any situation as it implies that only half of the person is 'accepted'. I describe myself as been mixed race when needed but even this can cause offence. Personally I don't see a difference between 'coloured' and 'a person of colour' In my opinion the best way to avoid causing any unnecessary upset is to not mention a person's colour at all which is easier said than done. At the end of the day there are many ways to describe people without mentioning the colour of their skin.