Bentinck-Scott was born in 1800. In his youth he frequented London society and had a commission in various British regiments. In 1824-1826 he represented Kings Lynn as a member of a parliament. He is never known to have dated any lady and his shyness and introverted personality just increased over time.
Bentinck-Scott inherited the title of the Duke of Portland in 1854. Although the title also gave him a seat in the House of Lords, it took him three years to take his seat there for the first time.
He stripped all the rooms of the Welbeck Abbey of their furniture, including tapestries and portraits, and stored them elsewhere. Then he moved to 4-5 rooms in the western wing of his estate, furnished them as little as possible and begun his plans for underground chambers. As for other rooms, he had them painted pink and installed a lavatory basin in all of them.
Bentinck-Scott was very introverted - he did not want to meet people and never invited anyone to his home. His rooms had double letterboxes, one for ingoing and another for outgoing mail. His valet was the only one he permitted to see him in person his quarters - he would not even let the doctor in. His tenants were told to ignore him if they saw him. All the other business with his solicitors, agents and an occasional politician he handled by mail correspondence. He maintained some correspondence with Disraeli and Palmerston.
Such enclosed lifestyle was prone to cause wild rumors of disfigurement or madness or wild orgies. However, contemporary witnesses and surviving photographs present him as normal-looking man (coincidentally looking a bit like Abraham Lincoln).
He created a complex on underground rooms with an army of hundreds of workmen. They included a large ballroom 174 by 64 feet (53 by 20 meters) wide, library 250 feet (76 meters) long, observatory with a large glass roof and a vast billiard-room. The ballroom had a hydraulic lift that could carry 20 guests from the surface and a ceiling that was painted as a giant sunset. But he never organized any party in this ballroom.
The eight tunnels under his estate totaled 15 miles (24 km) and connected the various underground chambers and above-ground buildings. One 1.25-mile (2 km) tunnel connected his coachhouse to Workop railway station and it was wide enough for two carriages. It had domed skylights and by night it was illuminated by gaslights. If Duke had a business in London, he would take the hearse to Worksop and had the whole carriage loaded onto a railway truck. Upon his arrival to his London residence in Cavendish Square, all the household staff was ordered out of sight when he hurried into his study through the front hall.
Alike many other contemporary British aristocrats, duke was fond of horses - his stables held 100 horses but he never rode them in his above-ground riding school.
His workmen were given an order not to recognize his presence (one who saluted him was reputedly dismissed on the spot) and they received all the instructions in writing. Otherwise he paid good wages and workmen received an umbrella and a donkey to come to work. Roads, farms and schools in his estate were kept in good condition and he created a large vegetable garden.
He ventured outside mainly in the night and was preceded by a servant lady who was carrying a lantern 40 yards before him. If he did walk out at day, he carried a coat and an umbrella and tried to hide behind them if someone addressed him. He ate only freshly-killed chicken and had it lowered into a heated truck that ran on rails through one of the underground tunnels to the house.
Duke died in December 1879. His cousin took over the unusual estate. He was buried in a simple grave in Kensal Green cemetery in north London.
Later widow Anne Maria Druce claimed that the duke was also his husband, a shopkeeper Thomas Charles Druce, who had died 1864. Widow claimed that his husband had faked the death of his alter ego to return to secluded aristocratic life and therefore his son was heir to the Portland estate. This "Druce Affair" dragged on in courts until 1907 when the Druce's body was exhumed - the widow had claimed that the coffin had been filled with lead. Speculators and the widow were charged with perjury.
Papers of the Duke are kept in the University of Nottingham.