Prince William is the second in line to the British throne, right after his father, Prince Charles. However, the forward-looking Queen Elizabeth II is already preparing her grandchild for his role as the future monarch.

In fact, Prince William’s training already started when he was still a teenager. “When William became a teenager, she would have him at Windsor Castle and would open the state boxes and guide him through papers,” Robert Lacey, historian and consultant to Netflix’s television series, “The Crown,” told People. “It was William’s constitutional education.”

The Queen and Prince Charles are said to have a “prickly relationship,” which probably explains why she opted to directly guide William instead. “There has always been a special closeness between William and the Queen, and she has taken a particular interest in him,” Lacy added. “It’s no secret that she and Charles have had a prickly relationship at times.”

However, Prince William’s training for the throne went beyond reading the papers that Queen Elizabeth gave him. The Duke of Cambridge underwent a two-year program to prepare him for his role as the future king.

To better prepare him for his future role as the British monarch, the two-year program exposed him to the different Whitehall departments to give him a clear understanding of how the government works. There are also lessons from constitutional experts, as well as briefings by former Prime Minister Sir John Major.

The training also included managing the Duchy of Cornwall, which he is set to inherit once Prince Charles becomes king. The two-year program also included solo foreign tours to Commonwealth countries. The training content was jointly designed by the Queen and Prince Charles.

In recent year, Prince William is more visible to the public after he quit his job as an air ambulance pilot. He is taking in more royal duties after having absorbed some of the responsibilities previously held by his grandfather, Prince Philip, who already retired.

Meanwhile, his younger brother, Prince Harry, remains very supportive of Prince William. “We’re involved in modernizing the British monarchy,” Prince Harry broadly explained their roles. “We are not doing this for ourselves but for the greater good of the people. Is there any one of the royal family who wants to be king or queen? I don't think so, but we will carry out our duties at the right time.”

Prince William Prince William, Duke of Cambridge, officially opens Brains Brewery before attending the Wales vs Ireland Six Nations Match on March 16, 2019, in Cardiff, Wales. Richard Stonehouse - WPA Pool/Getty Images