'Ghost' photographed in historic Scottish castle

Okay, somebody explain this. Every word is true. I arrived at Lauriston House, near Edinburgh, some time before 2pm on Saturday January 4th. In one of the photos you can see my car parked at the left hand side. It was locked and bolted - and the custodian had to switch off the alarm system (motion) when he arrived and unlocked the place. There was NOBODY in the house when I got there. (Several people had rung the bell and knocked the door, wondering if they might see inside.) I took a quick series of photos. On bringing them up on my computer, I was going to edit them a bit, but noticed the strangest thing – a figure at one of the windows, who I SWEAR was not there when I arrived. I have not edited this photo in any way. It is exactly as it came on the camera. (Okay, I drew a red arrow to one of the windows so you know where to look.) I have enlarged the insert of the window, and added “smart fix”, just to sharpen it up a bit. Now, say what you want, but there is a figure at that window, and they are not wearing modern clothing. Additionally, I had taken another couple of photos in quick succession – which you can see here, and the figure appears to have moved! (Enlarge the image and have a look for yourself.)
I give you my word:

(1) There was NOBODY in the house when I arrived. It was bolted and shuttered, apart from a couple of upper-floor windows. The place was deserted and in darkness. Nobody arrived until around 15 minutes after I got there, when the custodian opened it up.

(2) I have NOT manipulated the pictures (apart from the red arrow).
As an aside, I once spoke to a lady (no names at this point) who hates being alone in that house when locking up and setting the alarms. She swears (and I have no reason not to believe her) that on one occasion while looking in a cupboard, and was pushed hard in the back, knocking her forward, but there was nobody there. And on another occasion, alone in the house, and while in the kitchen area, the large gong in the hallway rang out. Seriously creepy. (Edit) Just to clarify... I was performing there this evening, and arrived before the custodian. I had to wait for him to unlock the door to permit entry AND switch off the (highly sophisticated) security system. Anybody moving in the house would have set the alarm off!)
PLEASE SHARE, PARTICULARLY WITH ANYBODY WHO IS INTERESTED IN THIS SORT OF THING.