... it doesn't sound like a post chaise from the description. The Bennets compare both the chaise and the servants' livery to their various neigbours', and as you say, a yellow chaise, led by a post boy in yellow, would be pretty distinctive, even from a distance. I think it would be like telling the difference between a yellow school bus (in North America) and a regular city bus or a touring bus. I wonder if the post horses wore a distinctive harness, or if they were obviously of lesser quality than privately owned horses.