Good review, Carl,
I think the strongest piece of advice was that about Becky's motivation. Kids often do get into 'shan't play' mode and refuse to come out of it regardless of logic. The key question is how do you want your readers to feel about it? Are they empathising with her or viewing her as an idiot?
Congratulations
John

She's definitely in the 'shan't play' mode at the beginning. I think the editor wondered why she was still in it at the end of the first chapter (after the amazing car etc). Well, err, she isn't really, so I didn't get that.