Smiling in the gentle sunlight, Prince Charles is seen on his 70th birthday photographed for the first time with his entire dynasty – two sons, three grandchildren, and another yet to be born.

Released today to mark the future king's milestone, the images, taken in the gardens of Clarence House in September, show Charles as few see him, a loving grandparent at ease with his surroundings.

He is accompanied by the Duchess of Cornwall, who takes centre stage at the heart of the family in this joyful portrait, the Daily Mail reports.

Grandpa Wales, as he is known by his brood, holds his first-born grandson, Prince George, five, on his knee, as the young prince, dressed in knee-high socks, shorts and loafers, smiles before bursting into laughter at something out of shot.

Charles is dressed formally in a pin-striped suit, sky-blue tie and loafers, yet looks at home with his family around him.

The Duchess of Cambridge, 36, in a £1,750 polka dot midi dress by London designer Alessandra Rich, is holding Prince Louis, aged six months, who offers an adorable chubby-cheeked smile.

The Duchess of Cornwall, 71, sitting hip-to-hip with her husband, is wearing a cream crepe day dress by Fiona Clare, adorned with two Van Cleef & Arpels' Libellule dragonfly brooches, one with diamonds and the other sapphires, which Charles bought her as a gift.

She is sitting close to Princess Charlotte, three, who is dressed in a blue dress by Mary Janes. At one point the duchess puts her arm around Charlotte's shoulders to point at someone off camera.

Privately, Camilla is very much a hands-on grandmother to her own five grandchildren, who amusingly call her Gaga. Behind Camilla, newlywed Prince Harry, 34, who is standing next to his brother, Prince William, 36, rests his hand on his wife Meghan's hip.

The Duchess of Sussex, 37, wearing a cream sleeveless Givenchy dress, would have been barely eight weeks' pregnant.

It is unclear whether the rest of the family would have been let in on the secret, as she was still so early in her pregnancy.

The prince has insisted that today will be a normal working day for his whole family.

He has two meetings at Clarence House and this afternoon will attend a tea party with his wife and 70 inspirational people also marking their 70th birthdays, at Spencer House in London.

Guests will include volunteers for a number of charities such as The Prince's Trust, The Silver Line and Barnardo's.

Tonight the Queen is holding a private party at Buckingham Palace for more than 600 guests to celebrate her son's milestone. In honour of the occasion, Charles has also guest edited a special edition of Country Life magazine.

In it, William reveals the lengths his father has gone to in his passion for the natural world – inviting some of the creatures living in his garden into the house.

So strong is Charles's love for the red squirrels at his Scottish estate, the heir to the throne has named them all and even allows them inside to explore.

Praising his father's commitment to preserving the countryside, William also described how Charles had installed 'hundreds' of bird tables at his Highgrove estate in Gloucestershire, which he goes round replenishing every day when he is there.

Speaking to the magazine, William said his father's passion for the environment was something he wanted his own children to inherit.

"My father's focus on the environment is something I've looked up to all of my life," he said. "His passion for the environment and the natural world is something I want to repeat in the way I raise George, Charlotte and Louis."

William also revealed how Charles, who is patron of the Red Squirrel Survival Trust, adores the creatures at Balmoral.

"He is completely infatuated by the red squirrels that live around the estate in Scotland – to the extent that he's given them names and is allowing them into the house!" he said.

According to one royal aide, the photoshoot turned into a "really happy family day". Another said: "It's clear the youngsters have a really lovely bond with their grandpa. He is very affectionate with them."

Writing in Country Life, Charles referred to his "alarming" 70th birthday and joked that he had "all the scars that go with" his milestone age. He expressed concern over the UK's position as a food producer and suggested it could give itself the edge by becoming the world's most environmentally friendly one.

"As a … small island, I cannot see how our food production could ever compete within the world's commodity markets," he said.

"Perhaps, though, we could seek to establish the United Kingdom as the most environmentally friendly food producer with a unique 'brand image', as an island offering the highest standards of quality and natural goodness?"