If you are a member, you must have full dress turn out. But guests should dress as "traditional" as they can. The Members have heavy woold jackets for the season, where Guests don't, so the Hunt suggests wearing proper colored jackets to stay warm.
I wore my show blouse, my stock tie with pin, and a black pull over fleece to remain with traditional colors.
If you are a member, you must wear your colors and your full proper attire. As you see, they do.