You guys seen the "Children's Ages in the Last Battle" thread. They kinda inadvertantly discuss Eustace being younger than Lucy. I have also heard that Lewis did not think he would write any books past VDT. So in that book Eustace could seem older, but by the time he wrote LB it seemed(and is implied) that Lucy is older. Unless I gone off the deep end which is entirely possible.
Most people on the other thread seem to agree Lucy is older; although, it is probably not by all that much. If nothing else, Lucy is certainly more mature than Eustace even if she is not chronologically older, but I suspect she is.
i aggree with ladyanneh lucy is older but not by much (maby a year at the most). or it could be very possible that lucy is the same age as scrub and poll.
lucy is at least one year older. most readers would not give her more than that. but the last battle states that jill and eustace were the only two still in school which says that lucy was definitely older than both of them.
I'm drawn to think he was younger than Lucy, too, even if at first (before he turned into a dragon) he always thought himself superior and in a way 'older' than Lucy.