He's clearly an old man with a long white beard. He looks to be wearing a robe (or is it a shroud).
Here's the gatehouse of the cemetery:
I've highlighted the image in purple. Sometimes it helps to see detail:
You can see the rest of the pictures from Glastonbury here. I've got a lot more ghosts:
http://ghastlydoor.com/haunted-photographs-4/
Here's a drawing I did for the article:

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