The Queen has paid tribute to Prince Charles on his 70th birthday, calling him a “duchy original” and an heir to the throne comparable with any in history.

At a Buckingham Palace dinner, the 92-year-old monarch raised a toast to her son and heir before family, friends and members of European royalty.

“It is a privilege for any mother to be able to propose a toast to her son on his 70th birthday,” she said. “It means that you have lived long enough to see your child grow up.

“It is rather like – to use an analogy I am certain will find favour – planting a tree and being able to watch it grow.

“My mother saw me turn 70, of course. And she was heard to observe that 70 is exactly the age when the number of candles on your cake finally exceeds the amount of breath you have to blow them out.

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“Over his 70 years, Philip and I have seen Charles become a champion of conservation and the arts, a great charitable leader – a dedicated and respected heir to the throne to stand comparison with any in history – and a wonderful father.

“Most of all, sustained by his wife, Camilla, he is his own man, passionate and creative. So this toast is to wish a happy birthday to my son, in every respect a duchy original. To you, Charles. To the Prince of Wales.”

Earlier, Theresa May led tributes to the prince, praising his “total” commitment to public services.

Opening a Commons debate to mark the occasion, the prime minister said the heir to the throne had spent his life “defying expectation and refusing to be categorised”.

Paying tribute to his role as a father, she said: “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.

Facebook Twitter Pinterest The Prince of Wales holds a birthday gift as he and the Duchess of Cornwall arrive for a tea party at Spencer House in London. Photograph: Steve Parsons/PA

“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.”

Jeremy Corbyn, known for his republican beliefs, also praised Charles’s commitment to public service and charity, and his passion for notable causes. He joked: “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.”

Corbyn added that the prince had shown a “consistent commitment to our often ignored natural world”, adding: “It is vital the principle that the royal family remains above politics is there.

“But Prince Charles as an ambassador for a country that does take seriously the scientific realities of climate destruction. I do wonder if there’s anyone on the planet who might be able to get that message through to the president of the United States [Donald Trump] – it could well be Prince Charles to do that.”