I stayed up WAY past bed time to listen to the radio show. Thankfully I'm a night owl because Bill Nighy didn't come on till the last hour of the 3 hour show.

You didn't miss anything. They talked about his other work more than Arthur Christmas. He said he had to audition and worked very hard to get the right voice, particularly when singing the song, "Make Someone Happy" in Grand Santa's voice.  He didn't mention James and don't think he mentioned any other co-stars either but I was getting a little tired.

Edi was reading comments from listeners and some wrote that they had seen ??? in Scotland but didn't say anything to them and now they regretted it. Edi said "You should have because he's a lovely, lovely guy." So I'm assuming it is James but didn't hear the original name.

So then I stayed up to watch the Arthur Christmas special on channel 5. Shout out to Viola for sharing this news with us!!
I am working on retrieving the recording and posting it. So check back or watch twitter for notification.