Mine would be a child of about seven with very supportive (but non-obtrusive) parents. If it was a girl, she'd practise enthusiastically every day and quickly get to a point where she was ready to take Grade One. She'd play all her pieces beautifully with lots of expression and unique, musical interpretation and get a mark like 138!
Then we'd do lots of other repertoire for a while before looking at Grade 3 pieces, which of course she'd sail though and get another mark like the last one. By then she'd have joined the local children's orchestra and love it to bits.
Before long we'd be looking at Grade 5..... and she'd still be only about 9.
Actually this is a bit like my wonderful little girl who is 8 now but nearly ready for her Grade 1. She's not practising quite as much as I'd like but today when she played 'the Vicar of Bray' she said 'oh I LOVE this piece' and played it really well. Then she played all her scales by heart and we did our call and response games, which she loves and does really well at.
And actually I know a child EXACTLY like the one described in the first paragraph but his mother's a cellist and he's been practising for half an hour to an hour EVERY DAY for four years, has a great teacher and is really good. How many young children have that kind of focussed support at home? Not that many, sadly.
