The Duke and Duchess of Sussex's first royal event as a married couple has seen Harry pay a moving tribute to the Prince of Wales for his charitable work and association with military regiments and units over more than four decades.
In Charles' 70th year the Duke described how his father's tireless efforts championing causes like heritage and vulnerable young people had inspired him and his brother, the Duke of Cambridge.
Speaking in Buckingham Palace's garden, he added that the Prince had also influenced many of the 6,500 guests, on the lawns of the Queen's official home, representing 386 of the Prince's patronages, and 18 of his military affiliations.
With his father standing behind him Harry said:
"It is your selfless drive to affect change, whether that is to improve the lives of those who are on the wrong path, to save an important piece of our national heritage or to protect a particular species under threat, which William and I draw inspiration from every day."
During the speech, a bee buzzed close to the duke and he fluffed his lines and quipped "that bee really got me".
Meghan and the Duchess of Cornwall broke into a fit of giggles as Harry tried to keep his composure.
Corporal Gregory Gilbert, from 2nd Battalion, Irish Regiment of Canada, which has Charles as its colonel-in-chief, said meeting Harry and Meghan was "wonderful" after he and his colleagues flew over for the party.
Second Lieutenant Reid Killen said:
"It felt like talking to my youngest son, the duke reminds me very much of him. He's always joking around and Harry has the same sense of humour."
His wife Janine said they talked to Meghan about Canada. The actress used to live in Toronto where she filmed the hit series Suits.
"I always thought the Royals were from far, far away but they are very down to earth," she added.
"They can meet anybody, anywhere and have the right words to say."
Harry began his speech by remembering those "affected by the tragic events at the Manchester Arena a year ago". The first anniversary of the bombing was marked by a memorial service earlier on Tuesday at Manchester Cathedral.
The duke who affectionately referred to Charles as "Pa" in his speech, added: "It is right that we take a moment to recognise the amazing work they do every day and how each member of our blue light services rise to meet the challenge of tragic events such as the attack a year ago."
He also poked fun at his father's famous "spider handwriting" notes given to royal aides and charity executives, setting out ideas on an issue: "Who amongst you has not known the joy, and perhaps trepidation, at receiving a handwritten note in response to some news shared from your organisation, urging you on and asking for more to be done to address this issue or that?"
Charles played a memorable role during Meghan and Harry's wedding on Saturday, walking the bride down the aisle after her father dropped out following heart surgery.
As the bride took her place by the groom Harry could be seen showing his appreciation and said: "Thank you, Pa."
Guests at the garden party ranged from representatives from the Gurkha Welfare Trust to the Parachute Regimental Association and the Royal Canadian Dragoons - all with a close association with Charles.
Harry ended his speech by saying to his father:
"You have inspired William and I and looking out here today, it is clear to see that we are not alone."
After stunning royal fans with her elegant wedding dress by British designer Clare Waight Keller, Meghan looked impressive in a chic dress by Goat and hat by Philip Treacy.
Harry was dapper in a morning suit and held his silk top hat in his hands as he greeted some of the guests invited to the event, which also marked Charles's association with military regiments and units.
One group of workers from global computer firm Dell, who have raised more than £300,000 for the Prince's Trust, congratulated the couple on their wedding.
Jyoti Bahia, 25, a project manager joined by four colleagues, said:
"That was incredible, there are no words to describe the feeling of meeting Harry and Meghan after their wedding.
"We congratulated them on their wedding and we all sort of said it at once - they said, 'thank you, very much'. They seemed really happy."
"You have created an incredible body of work that has and will continue to make such a huge difference to so many people's lives both here and around the world."
Later Charles spoke to Harry Keane, 14, a police cadet who gave emotional support to officers three days after the Manchester Arena bombing.
Harry said meeting him was "interesting" and added:
"I think it's very special and I like the fact that someone high up in power is caring for the youths and pushing the youths because we are the next generation."