Game, set, match! Wimbledon serves up stellar returns

Amid the green and luxurious surroundings of Wimbledon—home of the world famous tennis championship—is a chance to make an unusual investment that could see returns of more than 200 percent.

Wealthy punters will be able to buy the next tranche of so-called debentures this year—a unique form of debt security that gives holders a guaranteed Center Court seat through the 13 days of the championship for five years.

The last time the debentures were issued by the All England Lawn Tennis Club, which runs the Wimbledon championships, the 2,500 debentures for 2011-2015 on offer fetched £27,750 ($46,365) each.

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If held to maturity, an investor will only receive £2,000 from their debentures. But because these debentures can be bought and sold—as well individual tickets—savvy tennis fan investors are flipping their seats for a handsome profit.

Julian Finney | Getty Images

"I think if you looked at the last issue, investors are thinking, 'I've paid £27,750 so if I'm looking at is as a financial instrument, I can sell all of my tickets for £90,000, ' As a financial instrument it's fantastic," Philip Brook, chairman of the AELTC, told CNBC in a phone interview.

"A tennis enthusiast will think, 'I've paid that money and watching all that Wimbledon is good value for money, ' " Brook added.

Retired English tennis star Tim Henman told CNBC that the debentures were crucial to making Wimbledon the pinnacle of professional tennis.

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"When you see the best players talking about Wimbledon being the best tournament, it's a powerful message and certainly we have to make sure we maintain our status and the only way to do that is keep investing," Henman said in a phone interview.

Selling price on the rise

Selling prices for debentures have seen a steady rise since 2009, where investors could flog their five-year ticket for around £30,000. But the three most recent debenture deals saw private holders sell their tickets for sums of £91,333, £84,000 and £96,250 each, showing a stellar profit off of the initial £27,750 investment.

The recent spike in the selling price was due to people buying the debenture toward the end of its date range so they are on the register to be guaranteed a debenture at the next issuance, should they agree with the price.

The AELTC also offers to buy single-day tickets or the whole debenture back, which could also post profits for the investor.

Wimbledon's organizers use the money from debentures to improve the stadium's facilities, with Center Court's roof being the most famous addition in 2009. Debentures were first marketed in 1920 to fund building of the world-famous court.

Tennis fans and investors

But who is buying up these top-range tickets?

"We have a debenture holder we know, who is a partner at a City law firm and owns it in his own name. Sometimes you see him here with a client, or his wife with her tennis friends. Some days his kids are here and other days he sells them," Richard Atkinson, finance director of the AELTC, told CNBC in a phone interview.

I'd love to win the Australian Open: Andy Murray

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"So that is somebody who is a tennis fan but there is financial component as well."

The AELTC have not decided on the debenture price for the next issuance, which runs from 2016-2020, but Brook said that the price is likely to be "significantly higher" than the last one as the economic picture across the U.K. brightens.

Debentures differ from tickets available for the general public, who have to apply for a seat through a ballot. Public tickets are also not transferable.

—By CNBC's Arjun Kharpal: Follow him on Twitter @ArjunKharpal