We're half in the Otherworld, Paradise, wherever, by the descriptions we get here. The ghostly bark, the fantastical peaks of Rum, and Keith's own thoughts of where he's been when Ewen lifts him. I gives a kind of ongoing sense of where he's going to be in a few minutes.

I think part of the reason for this is the date of publication of the book. Everyone reading it would have experienced WW1 in some form, and the 'flu pandemic. There had to be some kind of surcease. It seems to have worked, going by the publication history. t was a popular book. I don't know what the zeitgeist in the Uk was regarding religion; I think WW1 was a watershed in that respect, but maybe harking back to, and quoting, religious figures of the past was a conscious choice. She worked in Oxford after all, and would probably have seen reminders of the Oxford Martyrs every day.

The lightness of the Epilogue is therefore something that's necessary to counteract all the tragedy, imo. Like the jig at the end of a Shakespeare play, no matter how tragic. Or the last line in Lord of the Rings. Life goes on, even though Ewen didn't want it to while he looked down on Keith's body.