King Charles and Queen Camilla were joined by fellow monarchs, King Carl XVI Gustaf and Queen Silvia of Sweden, for a special tree planting at Windsor tonight.

The Swedish Oak is a gift from the Scandinavian sovereign to celebrate the British royals’ coronation in May 2023 – two years on Tuesday.

Quercus robur, to use its Latin name, is taking up residence in Home Park on the Windsor Estate.

It has come from the Royal Nursery at Sollidan Palace, the Swedish Royal Family’s summer residence, and will be twinned with a Swedish oak which will be planted at the Royal Djurgarden in Stockholm.

The two kings, accompanied by Queen Camilla, walked companionably down from the castle together, while Queen Silvia – who was using a crutch following surgery on her foot – arrived separately by car.

Charles and Carl immediately began chatting to staff from the Crown Estate and their Swedish equivalents so enthusiastically that Queen Camilla was eventually forced to go up and give her husband a slight pat on the back to encourage him to come and help dig as they had another reception to go to.

Laughing he eventually followed his wife to the spot where the tree was waiting to have the last few spades of soil dug in.

The King told his friend and fellow monarch that he was ‘busy planting lots of trees across the estate’ and then invited him to take up a spade once used by his great-grandfather, King Gustavus V, to plant another oak tree in Windsor Great Park in 1908, which still survives today.

A member of Crown Estate staff said: ‘This spade was used to plant a tree by the king’s great-grandfather in 1908 in Windsor Great Park and we went to see it the other day. It is doing very nicely.’

After digging in several spades full, Charles said: ‘I think that will probably do it. It may have some lumps in it.’

King Carl started pushing the earth down with his foot, telling Charles: ‘You know what’s it like. The trick is to do this. You know the drill!’

‘You do it well,’ said Charles.

Both kings also gave the tree a little shake for good luck. ‘I am so glad you do that as well,’ the king smiled.

It was then the turn of the queens to be given a watering can each to finish off the job.

‘There we are,’ said Camilla, ‘we are going to give it a good splash of water.’

‘Put the whole lot in,’ she said encouragingly to Queen Silvia.

‘On this side, darling, this side,’ said King Charles. King Carl joined in : ‘Yes, here, behind.’

Carl was particularly glad to see the spade had been used by his great-grandfather. ‘1908!’ he said delightedly.

‘Can you see the tree from here?’ Charles asked his staff, referring to the previous oak. 

There was even more tree-talk amongst the two sovereigns, with Charles assuring his Swedish counterpart: ‘I shall keep a very good eye on it. If we are very lucky it will take to the soil and we will keep it watered. Thank you very much, you are so kind. Have you planted my tree?’

He added, pointing to the castle: ‘Don’t worry, I can keep an eye on it from over there for you! ‘

As he turned to leave, Charles said as an aside: ‘The good thing is that it is near the Pope’s tree.’ Staff explained that had been given as a gift by the late Pope Francis five years ago.

The King thanked the Swedish royal family’s gardeners for the tree, and Camilla said it was beautiful.

Today was a jam-packed day for Charles and Camilla because, after the tree-planting, they dashed off to attend a Reception for the Victoria Cross and George Cross Association at Windsor Castle alongside the Prince of Wales.

Prince William appeared in high spirits at the event, having just returned from his anniversary trip to the Isle of Mull with Kate.

After meeting locals and visiting the location’s tourist hotspots, William and Kate enjoyed a romantic getaway at a rented and isolated self-catering cottage for two – 14 years after they tied the knot at Westminster Abbey in 2011.

Meanwhile, Sweden’s longest-reigning King has had an equally busy past few days since he marked his 79th birthday at the Royal Palace in Stockholm yesterday.

Celebrating among them was the newest member of the Swedish royal family, Princess Sofia and Prince Carl Philip’s baby, Princess Ines Marie Lilian Silva.

The occasion saw Princess Sofia of Sweden and Prince Carl Philip’s newborn daughter, Princess Ines Marie Lilian Silvia, make her first public appearance on her grandfather King Carl XVI Gustaf’s birthday.

On the same day over in the UK, King Charles made a poignant message about his experience with cancer.

In the message, the King described the ‘daunting’ and ‘frightening’ experience of being told you have cancer.

In what has been described as his most ‘poignant’ and ‘deeply personal’ words about the illness fifteen months after his own diagnosis, the monarch also revealed he had taken inspiration from the late Dame Deborah James.

She urged sufferers, he said, with moving magnificence to ‘find a life worth enjoying; take risks; love deeply; have no regrets; and always, always have rebellious hope.’

His Majesty opened up in a message to fellow sufferers as they were invited to Buckingham Palace yesterday to recognise the incredible work of community-based cancer organisations.

The King is himself still undergoing regular treatments as someone ‘living with cancer’, although aides say his recovery continues in a ‘very positive direction, as reflected with the very full national and international diary programme’ he is undertaking.

The personally-penned message has added significance given that his daughter-in-law, the Princess of Wales, was also diagnosed with cancer within weeks of his own last year and underwent preventative chemotherapy.

In his message, Charles took pains to personally thank those who so ‘selflessly’ work giving care, comfort and reassurance to the 390,000 people who receive a new cancer diagnosis across the UK each year – more than 1,000 a day -as well as those working to treat the disease, research cures and fundraise for them do do so.

‘Each diagnosis, each new case, will be a daunting and at times frightening experience for those individuals and their loved ones,’ he wrote.

‘As one among those statistics myself, I can vouch for the fact that it can also be an experience that brings into sharp focus the very best of humanity,’ he wrote.

‘It has certainly given me an even deeper appreciation of the extraordinary work undertaken by the remarkable organisations and individuals gathered here this evening, many of whom I have known, visited and supported over the years.

‘And it has reinforced what I have long observed during these visits – that the darkest moments of illness can be illuminated by the greatest compassion.’

He added with added poignancy: ‘You have my whole family’s deepest admiration and gratitude.’

The King was diagnosed with an undisclosed form of cancer in January last year following routine surgery for an enlarged prostate.

Buckingham Palace have not confirmed what form he has, but have ruled out it being connected with his prostate issue.

They have also not disclosed what treatment he is still undertaking.

But there is little doubt that Charles has been more open about his diagnosis and medical treatment than any other monarch in history.