I just came across another haunting associated, rightly or wrongly, with Oliver Cromwell. From Paranormal Cambridgeshire by Damien O'Dell, p23, at Sidney Sussex College in Cambridge, where Cromwell had studied:
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Our story begins at 1 a.m. on 1 November 1967 - around the time of Halloween that most appropriate of haunting times. Third-year student John Emslie went to visit his friend Peter Knox-Shaw at Sidney Sussex. He decided to wait and to read in Knox-Shaw's room until his friend returned and as he waited he felt a presence and saw a partial apparition - what looked like a large mouth. At the same time Emslie sensed a gripping feeling in his neck and he also felt cold. Next he saw a floating, pale yellow, emaciated head without ears. The terrified student fled the room, close to panic. Some time afterwards Knox-Shaw himself returned, unaware of his friend's experience. He later recalled that on entering the room he experienced both cold and fear, without any logical reason. The strongest impression, however, was of a pungent, peculiar smell, but he saw nothing. He left his room again and soon bumped into Emslie. The two friends compared notes and Emslie recalled that he, too, had noticed the smell, which was like slightly rotten raw meat.
Linda Nield-Siddall was alone and half dozing at about 4.30 p.m. the next afternoon in her fiancé's, Mike Howarth's, room on the third floor, directly above that of Knox-Shaw. She looked up to see near the light switch, a large pale-blue and purple eye. This eye continued to come and go for some ten minutes. Linda was unaware of the events of the previous evening but was nonetheless nervous and left her room in a hurry. A number of similar incidents were experienced by other students including another sighting of the eye and reports of unusual coldness.
[...]
The witnesses to these strange events never varied their testimony. Over twenty years later the writer Geoff Yeates managed to track down two of them to interview for his book Cambridge College Ghosts, and they stuck to their strange story. Their view was that the paranormal events were directly connected with [...] one Oliver Cromwell.