Once a tourist paradise and one of the two most important conservation areas in Kenya, the northern region of Laikipia has been a tribal battleground for months.
Several Kenyans have been killed and driven off the land by invaders from the Samburu, Pokot and Masai tribes who are heavily armed and use ammunition made in government factories.
Mr Voorspuy, a co-owner of the Sosian Ranch, ran horseback safaris for decades with his wife Cindy.
He rode out to inspect one of three homes torched by invaders on Sunday morning amid reports that hardcore Samburu militia were still on the rampage.
His horse was found shot dead at noon and his body found a few hours later.
Mr Voorspuy, a former officer in the Life Guards, had worked hard with other locals to protect African farms against the marauding gangs.
But on Sunday night efforts to retrieve his body by his family in a pickup were met with a hail of bullets.
Three miles away, family friends said, Kenyan police numbering up to 250 with two armoured vehicles refused to intervene.
“His body has been seen by our scouts and is being held by the militia in the burned out remains of one of the three houses destroyed at the weekend,” a family friend said.
The Laikipia region is a favourite safari destination with Britain’s Royal Family.
It is also the most important British army overseas training area where troops prepared for combat operations across the region in facilities that cost £100m.
Tens of thousands of cattle have been driven onto Kenyan and foreign-owned ranches, alongside armed militia.
The militia is suspected of close contacts with members of parliament and government figures and there is real concern that northern Kenya is part of a failing state.
President Uhuru Kenyatta has been bitterly criticised for failing to stop the land invasions in which several Kenyans have been killed.
Elephant, lion, buffalo and all manner of other wildlife have been cut down with machine guns by the militia.
Kenya has general elections in August when tribal violence is certain to escalate given the vast number of weapons now in circulation.
On Friday, Cindy Voorspuy said in a message to Sky News: “Archie, my son, is still in the thick of it trying to keep the peace and protecting his herders’ cattle, game and staff…there will be more troubles to come…Just worry for Kenya.”
Mr Kenyatta is understood to be reluctant to intervene ahead of the elections.
He was indicted by the International Criminal Court in the Hague and accused of crimes against humanity over atrocities in the 2007 elections.
The case was dropped in 2014 after the prosecution failed to produce enough evidence but they blamed witness intimidation and lack of cooperation from Kenyan authorities.