I've been down a proper research rabbit hole on Borley Rectory this week, and I've got to say, the more I read the original documents and newspaper archives, the less impressed I am by the "most haunted house in England" claims. Most of what we "know" about Borley comes from Harry Price's investigations, which... have some methodological issues, to put it mildly.
Price had a reputation to build. He was a stage magician turned paranormal investigator. Is anyone else bothered by the fact that some of his "evidence" was later disputed by other investigators? The poltergeist phenomena at Borley seems to get less credible the more closely you examine it.
That said, something genuinely odd was happening there - the witnesses weren't all mad. But were they experiencing a genuinely paranormal haunting or were they experiencing a combination of suggestion, house settling, and genuine (but explainable) odd events that got mythologised?