Black whoosh seen in State bedroom

I was visiting Penrhyn Castle recently with a friend when we went into the State Bedroom at the top of the Grand Staircase and spoke to a room steward I had not seen before. He explained that he had heard of me due to my name being on the cover of the Penrhyn Ghosts book but had never met me before. He said that he had recently had an experience that he wanted to tell me about. He was standing at the top of the Grand Staircase whilst being a room steward when he suddenly became aware of a horrible smell. He described it as, "A smell like something had died!" He looked around to try and find out where the smell was coming from. He went into the State bedroom but nobody was in there. He walked past the dressing room, past the toilet and onto the top of the secondary staircase. He still didn't see anyone or anything that could be responsible for the awful smell. He said that as he walked back into the State Bedroom he saw a black shape move past him very fast and it disappeared towards the top of the Grand Staircase. I said, "It was a black whoosh!" He was surprised that I knew what he was talking about. I explained that several people have experienced similar things happening in different parts of the castle, such as the Scullery and Slate Bedroom. He said that he wondered at the time if it could have been his own shadow, so he went back the way he had just walked and came into the State Bedroom again, to see if he could recreate the back shape and movement. It did not happen. It was definitely not his shadow.

He also told me that he had taken a photo of the large mirror at the top of the stairs by the Nursery Bedroom in the Keep. He put the photo onto his computer at home and was very surprised to see a black figure standing behind his left shoulder in the photo. He said that when he took the picture nobody was around.

Can you spot the reflection of the black figure behind the man taking the photo in the centre of the picture?

Please let me know if you have had any experiences at the castle either as a room steward or as a visitor. This week is Halloween week and lots of interesting things have been planned. Hope to see you there!
http://www.nationaltrust.org.uk/penrhyn-castle/things-to-see-and-do/events/