Queen Elizabeth has always been in full support of Prince William and Kate Middleton as the future of the British monarchy.

The claim was made by royal expert Andrew Morton, who has written a new book about the reigning monarch titled "The Queen." The bestselling author, known for being Princess Diana’s biographer, has previously written books on other members of the British royal family, including Meghan Markle and Princess Margaret.

Morton’s latest book coincides with the Platinum Jubilee, which marks Elizabeth’s 70 years on the throne.

"The thing about Kate is the queen was impressed that she adored and loved William for himself, not for his title," Morton told OK! Magazine on Wednesday.

QUEEN ELIZABETH WAS ‘PRACTICALLY SKIPPING’ FOLLOWING PRINCE WILLIAM, KATE MIDDLETON’S WEDDING, AUTHOR CLAIMS

Queen Elizabeth Kate Middleton

Queen Elizabeth ll has long supported Catherine, Duchess of Cambridge. (Anwar Hussein/WireImage)

"She spends a lot more time supporting and nurturing the relationship between William and Catherine than she did with Charles and Diana. It’s pretty clear she wasn’t going to make that mistake again."

While the reigning monarch saw the couple "very much as the future," the royal household needed some convincing.

The Duke and Duchess of Cambridge met in 2001 as students at the University of St. Andrews in Scotland. William told The Telegraph they were friends for over a year before a relationship blossomed.

While the tabloids reported that the couple called it quits in 2007, they had reportedly gotten back together later that year. William proposed to Middleton in 2010 during a vacation in Kenya. The couple tied the knot in 2011.

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

Kate Middleton

Kate Middleton became the Duchess of Cambridge when she married Prince William in 2011. (Photo by Samir Hussein/WireImage)

"Everything that happened in [Kate and William’s] relationship was quite strategic, quite thought through, after a period of time," said Morton. "In the beginning, nobody in the royal household expected for a second that the university romance with Catherine and William would continue for any time after they graduated, like most college romances which disintegrate under intense scrutiny of jobs and geography."

Morton’s book revealed that the queen, 96, was said to be elated after the couple officially tied the knot.

"The queen was positively playful on the day of her grandson’s nuptials, ‘practically skipping,’ according to one observer, absolutely thrilled at the way the public had reacted to the royal newlyweds," Morton wrote in an excerpt published by The Mirror.

"She had a sense that the future of the royal family, her family, was so secure," he continued. "The monarchy was once again held in admiration and affection by the masses."

CLICK HERE TO GET THE FOX NEWS APP

Queen Elizabeth Prince William

Prince William, seen here greeting his grandmother Queen Elizabeth, is second in line to the throne. (Pool/Anwar Hussein Collection/WireImage)

William’s royal responsibilities have increased significantly since the royal wedding.

For the first time, the 39-year-old attended the State Opening of Parliament this month, accompanying his father, Prince Charles, and his wife Camilla, Duchess of Cornwall.

Buckingham Palace announced that the queen wouldn’t attend for the first time in nearly 60 years, as she struggles with difficulties in getting around. It noted that the decision was made in consultation with her doctors and that Elizabeth had "reluctantly" decided not to attend. Charles, 73, who is first in line, read the Queen’s Speech on her behalf.

Also for the first time, Elizabeth asked William to represent her following the death of a foreign ruler. The prince traveled to the United Arab Emirates to pay condolences following the death of His Highness Sheikh Khalifa Bin Zayed Al Nahyan, president of the United Arab Emirates and ruler of Abu Dhabi. He met with Sheikh Mohammed bin Zayed Al Nahyan, who has been appointed president of the United Arab Emirates.

PRINCE WILLIAM AND KATE MIDDLETON TO LEAD QUEEN ELIZABETH’S PLATINUM JUBILEE CELEBRATIONS

Princess Diana biographer Andrew Morton

Andrew Morton poses with a copy of his book, ‘Diana: Her True Story – In Her Own Words,’ at his home in London on Aug. 24, 2017. (Chris J. Ratcliffe/AFP via Getty Images)

William was likely tapped for the trip due to the queen scaling back on her overseas travel due to her mobility issues.

William and Middleton, 40, share three children: Prince George, Princess Charlotte and Prince Louis.