Companies with a founder as chief executive were 25% more valuable than public companies with no significant family control, Villalonga found.

FORBES: The Kochs' Crazy Dividend Policy Is Normal For Family-Controlled Firms

The choice of buyer has strengthened speculation that Mr Middelhoff and Juan Villalonga, Telefonica's boss, plan to forge an ever-tighter German-Spanish axis.

ECONOMIST: Bertelsmann

The Spanish government blocked a previous plan for Telefonica to merger with the Netherlands' KPN, prompting the resignation of chairman Juan Villalonga.

BBC: BT 'considers Telefonica merger'

Things get better after management has passed to professionals and later generations of family members still own large stakes in these companies, Villalonga said.

FORBES: The Kochs' Crazy Dividend Policy Is Normal For Family-Controlled Firms

Mr Villalonga, like other telecoms bosses, has had to cut costs (9, 300 jobs will go this year) as leaner companies have invaded his turf.

ECONOMIST: Telephones from Toledo to Tierra del Fuego

Villalonga and Raphael Amit of the University of Pennsylvania studied the companies of the Fortune 500 between 1994 and 2000 and uncovered several surprising facts.

FORBES: The Kochs' Crazy Dividend Policy Is Normal For Family-Controlled Firms

Hispania unveiled a new financial backer in the shape of Spanish businessman Juan Villalonga, who will work with team owner Jose Ramon Carabante to stabilise the team and attract new sponsors.

BBC: Russian supercar firm Marussia takes over Virgin Racing

The favourite target of the critics is Juan Villalonga, a pal of Mr Aznar from his schooldays, whom he made head of Telefonica when it was state-owned, and who is now one of the richest men in the land.

ECONOMIST: A new Golden Age