KATE MANSEY: Thank goodness for Solo-Sophie, the Duchess of Edinburgh. She has a grueling long-range agenda – but it is crucial to our barely stretched monarchy

While all eyes have been on the state visit to Kenya, followed by the celebrations of Charles’ 75th birthday, some other royal appointments have attracted less attention.

Sophie and Edward in particular emerge as under-the-radar royals, taking on the pressure of important visits – many of them long-distance – while other frontline royals are involved elsewhere.

Last week, Sophie, Duchess of Edinburgh, returned from a five-day visit to Canada, where she is Colonel-in-Chief of the Lincoln and Welland Regiment and patron of two hospitals in Toronto.

Last month the Duchess arrived in Ethiopia with little fanfare and no large entourage.

It’s only been eight months since Prince Edward’s wife, Sophie. became the Duchess of Edinburgh. She has embraced the role and her ever-increasing royal responsibilities. Sophie and Edward are pictured at the Order Of The Garter Service at Windsor Castle in June

The new power quartet that King Charles relies on: The Prince and Princess of Wales are Prince Edward and Sophie, Duke and Duchess of Edinburgh, as they leave Westminster Abbey after the coronation. Prince Louis walks between his parents

The hardworking Duchess of Edinburgh became the first royal to visit South Sudan last year

Her private secretary Alexander Stonor and her deputy private secretary Annabelle Galletley were the only ones traveling with her.

Meanwhile, her husband Prince Edward, the Duke of Edinburgh, has his own full itinerary, including recent visits to Turkey and Bahrain on official business.

They are, in other words, extremely busy – even if it’s other members of the royal family who dominate the country’s Instagram feeds.

There is plenty to do. With the Duke and Duchess of Sussex leaving for a new life in America and the Duke of York out of the picture, Charles III’s slimmed-down royal family is starting to look spread thin.

Although the king is in good health, he will still celebrate his 75th birthday later this month, along with a 76-year-old queen who is known to hate long-distance air travel.

Over the next decade, their foreign policy will need to be carefully considered.

William and Catherine have youth on their side, but they also have a young family to juggle and are determined to give the children as normal a childhood as is possible under the circumstances.

Thank goodness, then, for Edward and Sophie, who share much of the royal burden, often the less glamorous parts.

At 59 and 58 respectively, time is still on their side. Their children are more independent now that they are older.

Lady Louise celebrated her twentieth birthday earlier this month; son James, now the Earl of Wessex, is 15.

Could there be a future role for Lady Louise once she completes her university education? Given her poise and maturity – like mother, like daughter – we can hope so.

Because it’s only been eight months since Sophie became Duchess of Edinburgh, yet she’s already done so much.

It’s clear she’s quickly becoming one of the most important – and hardest-working – members of the royal family.

She doesn’t always get a lot of publicity for her work and that’s certainly what she’s looking for, but it’s still of great value.

Sophie has traveled all over the world. She was the first Royal to visit South Sudan and last year flew to New York to tell the UN that women’s rights had ‘backslided’ in Afghanistan.

All this is done with her innate refinement and elegance.

Last week, she visited a rehabilitation center in Canada and proved her sobriety by taking off her pumps and donning a stocking harness to better understand how medics treat their patients.

Illustrating both good manners and thoughtfulness, Sophie wore a special diamond maple leaf necklace that has been in her collection since 2013.

Showing she’s a good sport, Sophie took off her pumps to try out the equipment at the Toronto Rehabilitation Institute in Canada last week

Sophie saw the crucial work UNICEF was carrying out at the Sabacare IDP Camp in Ethiopia in October

The Dukes join Prince William to meet global conservation leaders at a private screening of the RHINO MAN earlier this summer in June

Her importance in the hearts of the Royal Family was underlined in June when the Duchess was invited to join Prince William to meet global conservation leaders at a private screening of RHINO MAN – a feature-length documentary that aims to tackle the illegal trade in wild animals highlighted.

Such a close relationship with the heir to the throne and an equally warm friendship with his wife, the Princess of Wales, will undoubtedly be crucial in the years to come.

It seems crucial now.