I agree with the BRCS team's consent on following the rule-books as closely as possible, but I think there's a bit of obsolete data here...

Leadership was built based on settings that had no such skill as Lead. For that reason alone, its only prerequisite is that your character has at least 6 character levels. Now, while I agree with that (right over the 1/4th threshold), the feat seems to good: even the wild mongrel wtih no ranks in Lead can choose Leadership as a feat!

I say that the prerequisites for Leadership change to: "Character Level 6, Lead 9 ranks."