It's lunchtime in Cape Town, and a stream of customers are lining up at the Nando's restaurant on Long Street. A cashier, Zimktha Loza, tries to take phone orders over the din of Portuguese-inspired music.

"I have regular customers every day," Loza said. "I hear their voice and know what they are going to order."

Long lines at Nando's, which opened its first eatery in South Africa in the late 1980s, are a common sight at outlets far away from Cape Town. The fast-growing spicy-chicken chain has 1,100 locations in 22 countries, helping make its original backer, Dick Enthoven, a billionaire.

The son of an insurance magnate, Enthoven kick-started the business by giving two entrepreneurs, Robbie Brozin and Fernando "Nando" Duarte, a loan to expand their chain of chicken restaurants in the early 1990s. Today, he owns more than 320 Nando's outlets in the United Kingdom.

The business accounts for half of his $1.1 billion fortune, according to the Bloomberg Billionaires Index. The rest of his net worth derives from Hollard Insurance Company Ltd, South Africa's largest closely held insurer. He has never appeared on an international wealth ranking.

"At its heart Nando's is a private family business," said a Nando's UK spokeswoman who asked not to be identified, citing company policy. "The principal backers in Nando's, shortly after its founding, are the Enthoven family who have provided private capital and significant business know-how to grow the business in South Africa and globally."

She declined to comment on Enthoven's net worth.

Nando's Afro-Portuguese-themed, quick-service restaurants are known for their signature peri-peri chili marinated chicken. A half bird sells for seven pounds ($10.27) in London and 57.90 rand ($4.70) in Cape Town.