Apparition?!

While I was in Chichester this morning picking up a camera case which I'd accidentally left at the restaurant yesterday I thought I'd take a walk around Chichester Cathedral.

There was an open door that I hadn't been through before so I popped my had round, and liking the look of the little alleyway, I took a picture.  I swear there was nobody there when I took it!  I can only assume they came out through another little side door and I just didn't see them............or is it a ghost!!??