escape yourself and gravity

Especially if you're a resident or native of England, I could use some help. I just finished listening to the audiobook and loved it. From what I can glean about Eton, James was either 13 or 15 when he entered. The Powell's Books website quotes a Publisher's Weekly review stating James' age as 15. I think this is the case, I can see him being one of the exceptional sixth-form scholars let in. I'm 99% positive I heard the narrator call Roger a sixth-form Oppidan. Sadly, it's hard to check these things in an audiobook, particularly when your only cue-points are the hour marks. *sigh*

So. Questions are:

1. Is James in sixth form and therefore 15?
2. Is Jolly R also in sixth form and therefore 15?

To my mind, Roger doesn't feel like he is James' elder, but it could just be James' charisma that makes Roger seem the same age. Anyone who has read the book (and even better who may have it on hand), can you help me out?

I'm obviously going to have to buy the paperback, though, because it has an epilogue setting up the sequel, which the audiobook sadly doesn't have.