Since arriving a year ago in Scotland, two Chinese pandas have fully lived up to their superstar status, according to delighted officials at Edinburgh Zoo.

The duo, Tian Tian (Sweetie) and Yuang Guang (Sunshine), have attracted hundreds of thousands of visitors, including Queen Elizabeth's daughter Princess Anne, actress Nicole Kidman, Chinese Ambassador to Britain Liu Xiaoming and a host of politicians and VIPs.

They have boosted membership of the Royal Zoological Society of Scotland by 20 percent and helped sell 70,000 cuddly panda toys.

In 2011, Edinburgh Zoo had 525,000 visitors, but since its Chinese guests arrived, it's expected that more than 800,000 will go through its gates to see them by the end of 2012.

"The first panda year has been a great success," said Iain Valentine, director of research and conservation at the zoo. "The pandas are very famous in the UK and even more popular than we had expected," he added.

When the two pandas first arrived, hundreds of people welcomed them off their specially adapted aircraft at Edinburgh airport. Many more gathered at the gates of the zoo to see them arrive safely.

Countless news organizations reported the event, with one newspaper declaring that "panda mania" had hit the Scottish capital.

In the months that followed, Tian Tian was named one of the BBC's Faces of the Year in 2011, and both she and Yang Guang were chosen to receive an honorary Scottish Thistle Award for their services to the Scottish tourism industry.

Adding to the unique accolade, the award was carved out of bamboo, their favorite foodstuff.

To celebrate the first anniversary, the pandas will be served extra "panda cakes", nutritional supplements containing eggs, rice and soya, said Valentine.

The pandas' specially chosen keepers have carefully steamed more than 400 of the cakes over the last 12 months, to make sure their star guests are kept as happy and healthy as possible.

Children visiting the pandas can choose to buy any number of panda-themed arts and crafts currently being advertised as the perfect gift at Christmas, and there are special presents hidden at different locations all over the zoo to find and keep.

Chinese panda Tian Tian plays at Edinburgh Zoo on Wednesday. [Photo/Xinhua]

Valentine said he and his staff have learned an enormous amount about Tian Tian and Yang Guang, but also about pandas as a species. "This knowledge is vital to the global panda conservation effort," he said.

Through their research, the zoological society "has been able to develop further understanding of the nutritional needs of pandas, something we will develop further over the coming years," he added.

The two pandas failed to produce a cub during their short breeding season in April, despite high hopes from the zoo and massive public expectation.

"Our future research will also focus on male panda breeding behavior, of which much less is known," said Valentine.

With the news in recent days that Britain's Prince William and Princess Kate are expecting their first child next year, hopes are high at the zoo that 2013 could prove a special year, too, for their own celebrity couple.

"Wouldn't that be great," said Valentine.

Timing is crucial during panda mating, as females only ovulate once a year, meaning the window in which Tian Tian can conceive can be as short as 36 hours.

Plans are now in place for next year's breeding season and preliminary preparations have already begun.

Valentine said next year's focus will be on synchronizing their breeding cycles with a strict "lights out" policy.

From the end of December, lighting levels inside both panda enclosures will stimulate natural light levels outside so when the sun rises, lights will go on in the panda enclosures, and when the sun goes down it'll be lights out and early to bed.

This is vital, as lighting levels dictate panda hormone levels.

Valentine plans to fly to China later this month to present an annual report on the two pandas' welfare. They are on loan to Scotland for 10 years, after which they will be returned to China.

Any cubs born during that time will stay with the mother until the age of two, after which they must be handed over to China.