I wouldn't trust mainstream nutrition advice coming out from any country with a >20% obesity rate. So maybe from Japan, China, Thailand, Indonesia or Buthan. But not from the UK.
USDA is responsible for pretty much all food and farming oversight, including animal products and fresh vegetables. Just because one of their initiatives produced a misguided food pyramid poster isn't reason to denigrate the entire institution.
I'm sure you enjoy mad cow disease-free beef and salmonella free vegetables and chicken eggs when you go to the supermarket. You can thank USDA for that.