@coracle Agreed.  Pity though, that he doesn't do voice work anymore.

Also, I think I'm agreeing with another view you expressed on here also - not being overly impressed with David Suchet's Aslan in the FotF radio drama's.  Whilst I think he did put in a good effort for the role, for me, he didn't sound lion-ish enough, one thing I did like about his performance though was his vocals were a bit unpredictable - sometimes being really loud or really quiet.  I think it that area he did capture the unpredictability of Aslan - not being safe but being good.

An actor I’ve recently had on my mind especially after watching Guardians of the Galaxy again is how awesome I think Lee Pace would do voicing Aslan. After recollecting some of his other roles like in The Hobbit and Pushing Daisies he always has the right richness in his voice. 

I love some of the other suggestions too and I know Lee Pace isn’t British but I really don’t think he needs to be.