Perched above the River Foyle on the outskirts of Derry, Prehen House is a striking example of Georgian elegance with a history steeped in scandal, heartbreak, and enduring ghostly legend. Built around 1740 by Andrew Knox, MP for Donegal, the manor was inherited through his marriage into the prominent Lenox-Conyngham family and intended as a grand statement of refinement. Yet within just two decades, it became the stage for one of Ireland’s most infamous tragedies.

Knox’s friend, John MacNaghten, was a once-respectable gentleman whose fortune had been lost to gambling. Welcomed into Prehen as a house guest, he soon overstepped the bounds of hospitality by charming Knox’s 15-year-old daughter, Mary Ann. Under a veil of secrecy, he persuaded her into marriage. When Knox discovered the deception, MacNaghten was expelled from the house. Mary Ann’s infatuation waned, but MacNaghten’s obsession did not — he shadowed her for years.

In November 1761, Knox attempted to take Mary Ann to Dublin, hoping to escape MacNaghten’s pursuit. Just ten miles from Derry, the carriage was ambushed. MacNaghten fired into it, fatally wounding Mary Ann, who died hours later. Her body was brought back to Prehen House and laid out in the very rooms where she had once grown up.

MacNaghten was convicted of murder and sentenced to hang. During the execution, the rope snapped — a moment that, in folklore, meant a condemned man could claim freedom. But MacNaghten, unwilling to be remembered as “Half-Hanged,” demanded to face the gallows again. His grim wish cemented both his fate and his nickname.

Over 250 years later, Prehen House is still said to echo with his presence. The Ghost Room, notorious among visitors, is the reported epicentre of activity: beds sinking as though an unseen figure has climbed in, disembodied voices, and an oppressive atmosphere that unnerves even seasoned ghost hunters. Skeptics have found themselves shaken too — one family friend recalled the distinct sensation of being hugged from behind, only to turn and find no one there.