The Paranormal Database has the basic story:
'The maid Agnes and her mistress were both murdered and robbed in the late sixteenth century, their killer being found not guilty (according to one story). Agnes still protests the miscarriage of justice. A lone male figure also haunts the building, though is said to be non-hostile.'
The museum details can be found here: visit link
Another ghost has recently been captured on film and reported in the local newspaper 'The Daily Echo' as follows:
'Ghouls on film
By Diana Henderson
GHOSTLY goings-on are sending shivers down the spines of museum staff at Poole.
They have captured images of a ghost in the machine of the CCTV at medieval Scaplen's Court, which has long been believed to be haunted.
However, this is no Civil War casualty or murdered maid, but a gent in a bowler hat, standing in the first-floor Solar Room of the old town museum.
He appeared on the CCTV screen, with his back to the camera, when the equipment was switched on at 9.45am and remained there until about noon.
When a visitor stood in the same place, the apparition immediately vanished.
Two museum assistants saw it and took photos of the screen, which shows a blurred image of the man's legs, but not the upper part of his body, which they could clearly see.
"I am normally fairly sceptical about paranormal activity so I was shocked when my colleague and I saw the ghostly figure so clearly," said museum assistant Gary Edwards.
"Viewing the CCTV images it didn't look as though visitors could see the man but we have previously been told by female visitors that they could feel a male presence in that room.
"We have taken a number of other photographs since to see if it was a trick of the light but it seems to be genuine," he said.
However, neither went up to the first floor sun room, which has graffiti from the Civil War period scribbled on its fireplace, and the ghostly figure has not been seen since.
"We have done a bit of research to try and find out if there's anything from the 19th century or early 20th century which seems to fit in. We couldn't find anybody who it might be," said Michael Spender, Poole Museum manager.
He added that groups which investigated paranormal events had recorded poltergeist activity in the museum.
7:01pm Tuesday 9th September 2008'