I'd go mostly red, but you can't beat the odd spot of HP.
JTiedes - HP sauce (HP stands for Houses of Parliament as this is where it was originally created) is a ketchup consistency sauce - brown, vinegary and full of spices - not Hot, just flavoursome and tangy - hard to explain really, but is a staple in bacon sarnies and fry-ups.
I'm going to guess HP is some form of steak sauce or an off kind of worcestershire. Regardless it looks more to my liking that ketchup. Hate that stuff unless it's mixed with worcestershire.
Trust me, best tasting pizza you will ever have. Its got the beautfiul garlic taste (perfect for pizza) with the peppery spice that gives the pizza the best background heat.
I've never tried eating any sort of sauce on sausage or bacon (i'm in the U.S. though). Might have to see if I can get ahold of some Hp after hearing it described though. The only description I read on this site makes it sound kind of like steak sauce. Is that close at all, or do I just need to go buy some?