Its irrelevant now anyway, as I thought a horse who was entered couldnt possibly be qualified, but turns out one of the runs I thought was an advanced was actually a 3*, so thats answered my question
Yeah, who needs 6yo Champs when you could just hit up a 4 star?!? Easy. Not sure why no-one's thought of this before.... perhaps as a 7yo you could retire from eventing (no $$) and go showjumping instead?
AN 6 year old horse was third in The intermediate championships which are run under advanced rules and the rule book does say that eligibility to compete in the advanced or intermediate Championships the age of the horse is 7.