Secret to our happy marriage? We're best friends...

PRINCE Edward lovingly described his wife as his "best friend" as he spoke about the secret to their long and happy marriage on their official visit to Nepal.

- By Emily Ferguson

The Duke and Duchess of Edinburgh, who celebrated 25 years of marriage last June, are today on the last of their six-day trip to Britain's oldest ally in Asia.

The couple's banter has been evident during their joint engagements and their friendly rivalry has come to the fore.

When asked about their good-humoured interactions and the secret to such a happy ship, during an interview on the fourth day of their trip, Edward said: "Because we're best friends." Nodding, Sophie said: "That's true." Asked if humour was important too, the Duchess added: "Oh, there's always got to be humour. Especially when you're travelling and you've got no idea what's about to happen. You've got to laugh." The ease at which they bring levity to their work will have helped the unprecedented situation they found themselves in last year.

After working quietly behind the scenes for decades, the couple found themselves taking on a more prominent role as they stepped up while the King and the Princess of Wales received cancer treatment.

The Prince of Wales also reduced his duties to support his wife and their three children through the difficult period. As result, the Duke and Duchess, both 60 became crucial members of the Firm almos overnight, increasing their workload te cover the many engagements both at hom and abroad.

They provided great support to th Queen and Princess Anne, who were als busy conducting royal duties up and down the country.

Sophie was thrust into the spotlight afte staying relatively under the radar whil fighting issues such as human trafficking sexual violence in conflict, preventable blindness, and championing women's rights.