I really like the certainty of the non believers/scientists here.
Can one/some of you clever folk tell me what you think might have been going on here then please, because we've been unable to get to the bottom of it.
The house I lived in before this one was a cottage converted from old stables.
Family members, friends, DH and I and several tradesmen and visitors all saw the same thing. Visitors and tradesmen told us they'd seen it when we'd not mentioned it to them so it wasn't something we'd suggested. It happened at all times of the day, different light levels and throughout the year. Curtains pulled/open/broad daylight or gloaming.
At knee height a black spot about the size of a ping pong ball (perhaps slightly bigger) would dart across the room then disappear. Always the sitting room, nowhere else in the house, but in different places in the sitting room. It would travel about 75cm or 1m and then disappear. It always went right to left.
It wasn't at all woo or spooky. Grown men, kids, elderly people all saw it and couldn't explain it. We had terriers who never reacted to it (and they were prey mad terriers who would go mad for a mouse etc). On occasion two people would see it at the same time.
Not saying it was a ghost, but what was it?