Now her earnings could go through the roof

But experts said the heptathlete, who already has a number of sponsorship deals in place, would have to be careful or she could end up with more endorsements than she can cope with.

Simon Chadwick, professor of sport business strategy and marketing at Coventry University Business School, said he expected the 26-year-old’s earnings to double from around £1m this year to £2m the next.

He said: “She’s had a pretty good year already this year.

“It looks like her earnings last year were somewhere in the region of £600,000-700,000.

“This year it’s looking like £1m already from her endorsement deals just in the run-up to the 
Olympics.

“She already has a strong catalogue of endorsements such as Jaguar, Powerade, British Airways, Aviva, Olay.”

He said athletes typically have performance clauses in their contracts that dictate how much they are likely to earn.

“For example if an athlete qualifies for the Olympic Games, they will receive a particular payment, and if they get into the final they will get another one, and then if they get a gold medal, they will get an even bigger pay-out.

“In simple terms, the better she does the more she’s paid.

“By winning gold she will boost the income from her existing contracts,” he said.

“It will be interesting to see if she will be able to renegotiate her existing contracts.

“In terms of bringing in new sponsors, I think this could be a bit of an issue for her.

“She’s already got, as far as I can see, seven endorsements and to sign more could be a strain on her. Once you get up to eight, nine, 10, that’s a lot of commercial endorsement deals to fulfil.

“Plus as she is already signed to Olay, then they are unlikely to want her to become associated with other beauty products, and the same with British Airways and other travel companies.”

“Her advisers and management need to work very, very carefully now as commercially she is very, very valuable.

“If you’re Jessica Ennis in January 2012 renegotiating a contract then that’s a very different position to if you’re Jessica Ennis renegotiating a contract tomorrow.”

But he added that it was a “sad reality” that female athletes did not earn as much as men from sponsorship deals.

“If they want to earn huge amounts, they are going to have to do it on a global basis,” he said.

“I think for Ennis to earn the same amount as say, Andy Murray, she’s going to have to get a much more global profile and typically female athletes just don’t have that kind of international profile.”