@aslanthelion I think you have found the answer: they are such cowards and children that Aslan doesn't want to scare them more than necessary.
(It reminds me of a place in the Bible where God said he would only show his back to Moses, because he couldn't cope with seeing God face to face. Lewis may be alluding to this as well)

The only other things I can think of are that Aslan doesn't want to face England, only his own country, and also that in our world he has a different name (so presumably he doesn't look like a lion, and this would be wrong for our world).

I did not notice that either except when it was pointed out to me. Maybe it's also that Aslan is showing disrespect to them?

I think it might be that in the Old Testament, humans could not look on the face of God directly. God is perfect, and humans are not.

As @coracle pointed out, Lewis may have been alluding the bullies seeing only the back of Aslan to Moses only seeing the back of God.

It may indicate that the bullies, just as every human child, are not perfect, so they would not be able to look on the face of Aslan, who is supposed to be Jesus.

Posted by: @jasmine_tarkheena

It may indicate that the bullies, just as every human child, are not perfect, so they would not be able to look on the face of Aslan, who is supposed to be Jesus.

I'm not sure that follows logically, though, considering plenty of imperfect human children — and adults, and other sentient beings who aren't perfect either — do look on the face of Aslan throughout the whole series of books.

I've also seen commentators interpret "They shall see only my back" as a reference to Moses's experience in Exodus 33, though what it's supposed to imply specifically in this scene at the end of SC, I don't know (again, not least because plenty of other people from our world, no matter how unworthy they may be, do get to see Aslan's face in the course of the stories).

I'm guessing that as @coracle said, Aslan simply doesn't want to frighten the bullies — whom he describes as mere "cowards and children" — any more than necessary. It may even imply that he doesn't think very highly of them! We've already been told that Aslan "seemed to know [Jill and Eustace's school] quite as well as they did", so we might well assume he's aware that none of the bullies they're about to confront would be benefited by meeting him face to face. Probably none of them are anywhere near the point of repenting and reconsidering their ways just yet, or else Aslan would surely give them the opportunity here.

I have read at least one commentary that considered this scene the weakest and least satisfying ending of all the Narnia books — unfortunately I can't remember who the writer was or what he/she said about it. But I would guess it may have been someone who never suffered severe bullying at a school that was totally ineffective in dealing with such matters and so the bullies repeatedly got away with it. I did go through something like that as a child (and, sad to say, even as an adult in one particular workplace) and I've always thought it was really cool that Jill, Eustace and Caspian, with the help of Aslan, gave at least one gang of bullies the fright of their lives and changed the whole school for the better!!  

It's true that all we fall short somewhere. You might remember that Eustace was a bully himself in VDT, and he still had some faults in SC and LB.

I think bullying is a thing that a lot of kids deal with. I haven't experienced any, so I'm grateful for that. Though having been in children's ministry, they had shared prayer requests about bullies in schools.

I don't know if I would say it's the weakest ending of any book in the series. It could also be to the point that a lot of TV or movies say that you stand up to bullies and fight back. I don't think CS Lewis have meant it to be that. He didn't intended for Caspian, Eustace, and Jill to fight the bullies (when Aslan instructs them to "use the flats, not the blade."). So it may be possible that Aslan didn't want to have any physical violence involved in dealing with the bullies.

Posted by: @courtenay

Posted by: @jasmine_tarkheena

It may indicate that the bullies, just as every human child, are not perfect, so they would not be able to look on the face of Aslan, who is supposed to be Jesus.

I'm not sure that follows logically, though, considering plenty of imperfect human children — and adults, and other sentient beings who aren't perfect either — do look on the face of Aslan throughout the whole series of books.

I've also seen commentators interpret "They shall see only my back" as a reference to Moses's experience in Exodus 33, though what it's supposed to imply specifically in this scene at the end of SC, I don't know (again, not least because plenty of other people from our world, no matter how unworthy they may be, do get to see Aslan's face in the course of the stories).

I can't think of any other times Aslan showed himself IN our world, rather than merely to people of our world.  Can you?

@coracle No, I can't either. Maybe that's just it — people who aren't actually in Narnia or in Aslan's country don't get to see any more of Aslan than his back?

I somehow don't think Lewis was trying to make a really significant theological point with this scene (or else he'd probably have made it clearer), but it's interesting to wonder about!

I’m curious to see what the new version will have him do for the scene, have him look intimidating or relatively harmless.

I’m still curious about what Lewis means by, “Then he lay down amid the gap he had made in the wall and turned his golden back to England”, since if he was lying down, his back would be facing towards the sky. If it helps to have a visual, there’s a fan illustration I’ve seen online of Gandalf from LOTR with Aslan in which they’re shown from behind, and Aslan is lying down in it, so you can’t even really see his back, much less his face.

Could it be that Aslan wanted to ignore the bullies since he knew they were no threat to him?  They were weak compared to the Lion, and he obviously didn’t need to defend himself from them.  And since he provided a safe way out of our world for Jill and Eustace the bullies could not do any further damage to them. It may have been Aslan’s way of saying, “Your bullying doesn’t mean anything anymore”. 🙂

Posted by: @narnian78

Could it be that Aslan wanted to ignore the bullies since he knew they were no threat to him?  They were weak compared to the Lion, and he obviously didn’t need to defend himself from them.  And since he provided a safe way out of our world for Jill and Eustace the bullies could not do any further damage to them. It may have been Aslan’s way of saying, “Your bullying doesn’t mean anything anymore”. 🙂

That’s a nice way of looking at it. I don’t know if you were responding to my last post, though, since that wasn’t what I was actually wondering. No worries, though.

@aslanthelion 

I was responding to the topic, although it could have been a response to your last post.  It is a very good topic and I am glad that you noticed important details like that in the story, 🙂

@narnian78 Thanks! 🙂

I’m still a little bit confused by this. Aslan says they’ll see only his back, but I we get these quotes: 

“Then he lay down amid the gap he had made in the wall and turned his golden back to England, and his lordly face towards his own lands.”

“a lion as large as a young elephant lying in the gap…”

If he’s lying down on his belly, it wouldn’t exactly be a straight view of his back like it would be if he was sitting. 

I want to add that there’s this piece of fanart of Aslan with Gandalf from TLOTR where they both have their backs turned, and Aslan is positioned like he’s described here in this scene, and it honestly looks a bit awkward.