Sir Richard Lexington Sutton, an 83-year-old Baronet, was attacked inside his £2m home in north Dorset on Wednesday night.
A woman also suffered knife injuries in the incident that happened at Moorhill, a large detached property in the tiny hamlet of Higher Langham, near Gillingham.
Police received a call from a member of the public concerned for the welfare of the occupants of the house.
When they got there they found Sir Richard with fatal knife wounds. He was pronounced dead at the scene at 9.15pm.
The woman, who is aged in her 60s, was airlifted to the Southmead Hospital in Bristol. Her condition was today described as ‘critical’.
Immediate police investigations identified a Range Rover linked to the attacks that was spotted travelling eastbound on the A303.
It was tracked by police as it sped across Wiltshire, Hampshire, Berkshire and Surrey before it was stopped in Hammersmith, west London.
A 34-year-old man from the Gillingham area was arrested on suspicion of murder.
He was subsequently taken to hospital for treatment to injuries that are not believed to be life-threatening.
Police have confirmed the arrested man is known to the victims.
Sir Richard was described as an ‘old English gentry landowner’ who was worth an estimated £301m and was at number 435 on the Sunday Times Rich List.