Elton Smith, 23, was also given 15 years for aggravated robbery and three years for possession of an unlicensed gun to run concurrently with his murder sentence.

His brother Wayne, 25, was jailed for seven years for being an accessory to the murder with a further six years added for robbery.

In a statement Jonkheid’s wife Liezel said: “Our family is very relieved at the conclusion of this chapter. We feel that the sentencing brings some justice, though it can never compensate for the loss of Klaas. Our thoughts go to the parents of these murderers.”

Jonkheid, the founder of The Consumer Psychology Lab, was killed in the summer of 2009, the victim of a carjacking in the Western Cape town of Stellenbosch.

He was based in Johannesburg but had travelled to Stellenbosch to attend the annual conference of the South African Marketing Research Association (Samra), where he was a member of the paper judging panel.

Jonkheid founded The Consumer Psychology Lab in 2005 after stints in brand management at Cadbury Schweppes and as head of research and strategy at advertising agency FCB South Africa.

The business remains in operation, led by Liezel Jonkheid and colleagues Ingrid Olivier and Marianne Engelbrecht.