John said he had a weird day the other day. He was sitting in the lounge room watching TV. I was out, so he was alone. Where he sits he can see part way up the hall. He thought he saw a movement in the hall. No sooner had he looked away, than he thought he saw it again. It seemed to be coming regularly and he realised the impression of movement was created by a flash of light. So he watched closely and the next time it happened he walked up the hall to see where the flash of light was coming from. It turned out to be a glass mobile I had hanging near the bathroom window which was spinning round in the wind and catching the sunlight. The sun has been changing its angle noticeably lately and this is now happening for a short time each day when it is sunny.

So mystery solved, but he said for a while it had him worried, thinking someone else was in the house.