Human remains have been discovered at the former home of a military historian who was jailed for stalking and for possessing an arsenal of illegal weaponry.

For the past four days there has been a heavy police presence at the former home of Kenneth Ward. Ward, 72, was jailed in December 2011 for indecent exposure and weapons offences after police found a huge haul of weapons including a loaded Luger pistol under his pillow and the cockpit of a second world war fighter plane with working machine guns at his remote cottage.

On Tuesday up to six officers began digging up a plot at Appletree Cottage in Chop Gate on the edge of the North York Moors national park. Police said they were working with a forensic archaeologist, after the discovery of suspected human bones. It is understood the cottage is now in the hands of new owners, but was previously owned by Ward’s family for more than 300 years.

A spokesman for North Yorkshire police said: “Although it is too early to say precisely how old these bones are, current forensic investigations suggest they are not recent and are likely to be several decades old. Specialists are being used to recover and examine them.

“We’d ask people not to speculate online about the nature of the bones while this process is under way.”

Ward’s neighbour Mandy Dunford said police arrived three days ago and there had been a lot of activity ever since. “They are searching the property and people in the Dale have been told that human remains have been found,” she said. “It’s very concerning.”

Dunford, 59, suffered a nine-year campaign of intimidation from Ward, who would creep around her property naked, sometimes dressed only in military boots, shouldering a rifle.

She revealed her ordeal in 2015 after Ward was released from prison and tried to move back to his home – but was prevented from doing so after intervention from the current chancellor, Rishi Sunak, Dunford’s MP.

Dunford said of Ward: “That man put me through hell, and even though he was prevented from coming back here I can’t seem to shake off his memory.”

Ward, an eccentric military expert, was arrested after police discovered a huge cache of bombs and live weaponry at his cottage. RAF bomb squad officers were brought in to carry out controlled explosions on the moorland above his isolated home.

Ward was subsequently jailed at Teesside crown court after admitting 11 counts of exposure, three charges of possessing a prohibited firearm and seven other firearms offences.

At the time Dunford, a retired police officer, said Ward’s behaviour became increasingly erratic after the death of his brother, Brian, in 2002.

She said: “He first started exposing himself to me around 2002 and would peer in through my windows with his wild staring eyes. He would run around the house at night, shouting and tapping on the windows. When I was working during the day he would come right up to me and follow me around wearing nothing but boots and socks.

“Sometimes he would climb a ladder and expose himself over the wall of his cottage, and once he confronted me on the lane and aimed a rifle at me. I turned and ran and heard five shots go off behind me, I was terrified.

“He had a favourite stone on the lane next to my house where he used to stand to watch me with his pants down and shirt pulled up. He would stand there for hours and hours every day. Terrorising me became the only focus of his life. I went to the police to report him but their response was hopeless.”

Five North Yorkshire police officers were subsequently reprimanded after an internal disciplinary inquiry concluded they failed to meet “appropriate investigatory standards”.