Sir Martin Sorrell has defended his bumper pay package, arguing that he has put three decades of his life into building WPP from a maker of wire baskets into a £21bn global marketing business.

Sorrell, whose total remuneration is likely to hit £70m when full details are revealed in WPP’s annual report in the summer, is set to face a backlash from shareholders at the company’s annual meeting in June.

Sorrell began the company by taking a stake in Wire and Plastics Products in 1985 as a vehicle to deliver his ambition of creating a global advertising powerhouse.

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The 71-year old said that it has taken over 30 years of sweat to build WPP, now the world’s largest marketing services company, and as a result he is worth every penny.

“WPP capitalised at £1m [at its start in1985],” he said, speaking at the Advertising Week Europe event in London on Monday. “Today it is capitalised at £21bn. I’m not a Johnny come lately who picked a company up and turned it round [for a big pay day]. If it was one five-year plan and we buggered off, fine [to criticise my pay]. Over those 31 years … I have taken a significant degree of risk. [WPP] is where my wealth is. It is long effort over a long period of time.”

In March, the advertising firm revealed that Sorrell collected what is believed to be the second-largest package granted to a FTSE 100 chief executive, behind only the £92m in shares and cash paid to Bart Becht while he was chief executive of Reckitt Benckiser in 2009.

Sorrell, who has previously faced a significant backlash from shareholders over his pay, pointed out that it was investors who have voted through WPP’s remuneration policies.

“Everything we do gets approved by shareholders, one way or the other,” he said. “In the last five years the share price has grown from 665p to 1645p. If there is a problem it is that the market capitalisation has grown from £8bn to £20bn. If there is a problem it is that we have been successful. It’s pay, I don’t like the word pay, it is reward for performance with risk attached.”