A man was hacked to death and his wife was wounded when three men attacked them with pangas on a farm in Ficksburg, Free State police said on Monday.
Christopher Preece (54) was attacked on Saturday night when he went outside to find out why the power had been cut to the Fleur de Lis farm, near the Lesotho border, said Captain Phumelelo Dhlamini.
"Preece fled to the house, but the attackers chased after him and continued the assault," he said.
He was declared dead on the scene. His wife, Felicity Preece (56) was stabbed several times.
Their assailants stole R3000 and a cellphone.
Police were alerted by farmworkers reporting for duty on Sunday morning.
Preece's wife was taken to the Dihladeng hospital, in Bethlehem, in a critical condition.
Cases of murder, attempted murder and house robbery were being investigated.
Preece was originally from north London and moved to South Africa after "falling in love with the country", The Telegraph claimed.
The Christian Democratic Party said the murder of Preece was an indication of the government's inability to deal with the scourge of farm murders.
Party leader Reverend Theunis Botha said the attack and murder had once again sent shockwaves through investment markets abroad.
"It seems as though the attackers came from Lesotho, which once again raises the question of whether it can be justified that South Africa involves itself in peace-keeping operations abroad, whilst it cannot properly protect home soil," said Botha.
He said the attack and murder of Preece also indicated the country's failure in combating rhino poaching.
Police could not immediately confirm whether Preece was a British citizen or whether he was the owner of the farm.