Is Lily really the same age as James?

[ghinghapuss]

No: HPFGUIDX 89473

I have a question regarding Lily Evens Potter.

Is she the same age as James Potter?

We all assume she is, putting her in the same year as him at 
Hogwarts, but I'm not sure that is so.  I'm looking for any canon to 
support the idea that they were both the same age.  And I really 
looking for specific canon information.  Not things like `when they 
left school they joined the Order' – which doesn't necessarily prove 
they left at the same time.

One reason this bothers me is in the pensive scene in Snape's Worst 
Memory, Chapter 28, OotP - American Ed., there is no mention of Lily 
in the exam room.  She comes in to our conscious as sitting by the 
lake outside.  It strikes me as odd that after the jolt of seeing his 
father in front of him in the Great Hall, Harry doesn't look for his 
mum.  Harry's attention is taken from James back 4 rows to Sirius, 
then on to Remus and then he thinks Peter must be here somewhere and 
actively looks for him before he finds Pettigrew sitting a few desks 
away.  Harry doesn't even think of looking for his mother.  Does 
anyone else think this is odd?  

Why wouldn't JKR have put Lily in the Great Hall if she is the same 
age and would be also sitting her DADA OWL?  Wouldn't James have 
glanced toward Lily after striking out the 'L.E.' he had doodled on 
his paper?  If he, as a 15 year old boy (with sex on the brain), was 
crushing on the girl that much, I imagine any thought of her would 
take his attention over to where she would be. 

The question is bothering me because my brain keeps coming up with 
all sorts of theory's concerning Lily and Snape or Lily and Voldemort 
etc. etc.  And the main reason why some of these theories don't work 
is because Lily and Snape are supposed to be the same age.  But are 
they?

Help.

Cheers Mandy.