In reply to Ian W: The lad who finished 2nd in his age group at the BRYCS final at ratho has led 6a (indoors). He's 7.
In reply to Ian W:
I think the lad who came second was 9 and I am sure is capable of leading much harder than 6a assuming you mean French rather than English 6a. If he is 7 he is huge for his age.
My son came 3rd and has led a couple of 6b+'s, at the Foundry, one on-sight, and is dead set on leading a 6c before he turns 9 in September.