Never been to Waverly Hills myself (bit of a trek from Warwickshire!) but I've read a lot about that staircase area and the cold spots there seem to come up constantly across different accounts from people who don't know each other. That consistency is what gets me interested.
From what I understand about the building's layout, that back staircase was heavily used during the TB years for moving patients, so if you believe residual energy is a thing, it makes sense that particular spot would hold something.
Did the cold spot feel localised, like you could step in and out of it, or was it more of a general drop in temperature for that whole section? That distinction matters I think because localised spots are harder to explain away with drafts or building ventilation. Would love to hear more detail from anyone who was actually there.