But news that Yang Guang and Tian Tian, the two Giant Panads housed at Edinburgh Zoo, are to return to China in October brings to an end an arrangement once loaded with hope and underpinned by a startling diplomatic exercise and tonnes of specially-imported bamboo.

The pandas will head home after their 10-year contract – which cost the Royal Zoological Society £750,000 per annum – came to an end.

Yang Guang and Tian Tian arrived in Edinburgh after the RZS board identified back in 2007 a need to secure some “rock star animals” to boost visitor numbers.

The idea led to years of negotiation, with talks led by the zoo giving way to a long, arduous process involving UK and Chinese diplomats, former First Minister Alex Salmond, prime ministers Gordon Brown and David Cameron – and quiet, powerful interventions from the Duke of York and Princess Royal.

Zoo visitors were enchanted by the new celebrity residents. Tricky and unsuccessful mating attempts and breath-by-breath accounts of the pandas’ encounters ensured blanket coverage.

At the time, Alex Salmond said the pandas’ arrival reflected “the growing relationship between Scotland and China, in terms of cultural, educational and economic ties”.

Six months ago, China’s Ministry of Foreign Affairs hailed the “enormous scope” for cooperation with Scotland, with Scottish exports to China growing from £113m in 1996 to more £1bn today.

Male panda Yang Guang eats bamboo in his enclosure as he bulks up ahead of breeding season at Edinburgh Zoo. He will now return home with his companion Tian Tian. PIC: PA/Andrew Milligan.

As symbols of diplomacy, the precious cargo of Yang Guang and Tian Tian may have helped deliver more than they could ever know. Hopefully, as with all ageing rock stars, they can now quietly fade from the limelight.

It's time for Edinburgh's 'rock star' pandas to fade from the limelight