Prime Minister Theresa May has led tributes to the Prince of Wales on the heir to the throne’s 70th birthday.

Gun salutes were fired in celebration of Charles’s milestone age as the prince spent the day working, ahead of a black tie party hosted by the Queen at Buckingham Palace.

The PM, opening a Commons debate to mark the occasion, said the future king had spent his life “defying expectations and refusing to be categorised”.

Royal visit to west Africa – Day Six
The Prince of Wales on his recent tour to Ghana (Joe Giddens/PA)

Mrs May told MPs: “Throughout the Prince of Wales’ life, his commitment to public service has been total.

“That is true of his royal duties, which see him performing well over 600 official engagements every year.”

She said his sons – the Duke of Cambridge and Duke of Sussex – were a “true credit to their father”, and said: “We as a nation are immensely proud of them and I am sure he is too.”

Mrs May added, referring to the death of William and Harry’s mother Diana, Princess of Wales: “Regardless of your background or resources, raising children is never an easy task. It is made all the more difficult when they suffer a devastating loss at an early age.

“So today, as Prince William and Prince Harry make their own way in the world and begin to raise their own families, I know I speak for all of us when I say they are a true credit to their father.”

Labour leader Jeremy Corbyn, a staunch republican, admitted that, although people have different views on the monarchy, being heir to throne is not an easy job.

He praised Charles’s public service and even confessed to having something in common with the prince.

“It might come as a surprise to many that His Royal Highness and I have something in common – we’re both, it seems, leaving it late when it comes to career progression, although he has had a lifetime preparing for this role,” Mr Corbyn said.

“People in this country may have varying opinions about the institution of monarchy but no-one would say being heir to the throne of the UK as well as 15 other nations is an easy job.”

National Memorial to British Victims of Overseas Terrorism
The Prince of Wales meeting Labour party leader Jeremy Corbyn at the National Memorial to British Victims of Overseas Terrorism in Alrewas, Staffordshire (Paul Ellis/PA)

Mr Corbyn added: “His Royal Highness has shown a commitment to public service and charity, and a passion for several notable causes, throughout his life.”

On the forecourt of Buckingham Palace, the Band of the Welsh Guards played a rendition of Happy Birthday in the prince’s honour.

The Royal Family also wished the nation’s longest-serving heir to throne “a very Happy 70th Birthday” via Twitter, accompanied by a montage of photos of the prince through the years.

As is tradition, a 41-gun salute was fired by the King’s Troop Royal Horse Artillery in London’s Green Park, while at the Tower of London, the Honourable Artillery Company fired a 62-gun royal salute, and at Westminster Abbey, the bells rang out.

Congratulations from around the world were sent to Charles.

The Welsh Guards at home and abroad recorded special video messages for their Colonel from troops in Iraq, Afghanistan, Germany, Chile and Canada, as well as in the UK.

The prince was spending the day holding meetings at Clarence House, before he and the Duchess of Cornwall have tea with a group of inspirational people who also celebrate their 70th birthday this year.

In the evening, the Queen is throwing a Buckingham Palace birthday bash for her eldest son and heir.

European royals and Charles’s closest friends and family are expected to gather at the glittering black tie party in the monarch’s London residence.

Charles was surrounded by his nearest and dearest in the official images marking his birthday.

In two photos released by Clarence House, the prince was pictured sat on a bench with his grandson Prince George, wife Camilla and granddaughter Princess Charlotte.

Stood behind the prince and his wife were the Duke and Duchess of Cambridge – with Kate holding Prince Louis – and the Duke and Duchess of Sussex.

The photographs are rare images of Charles with his three grandchildren, whose number will increase to four when Meghan gives birth next year.

Charles is beginning his eighth decade from a position of confidence, with his charitable work in full swing, his sons forging their own public lives and Camilla by his side providing support.

The photoshoot was staged in the garden of Clarence House in September, and appears to show a “before and after” of the moment the photographer said “smile for the camera”.

In one image, the royals are looking straight ahead and smiling, while in the second Meghan is bending over as she laughs, Camilla has put her arm on three-year-old Charlotte’s shoulder and is pointing at something, while George has a fit of the giggles.

Baby Louis, who is six months old, looks happy and content in the photos and has almost grown a full head of hair, while his big brother, five-year-old George, dangles his long legs either side of his grandfather’s knee.

The pictures were taken by Getty photographer Chris Jackson.