The move is “a huge affirmation and statement about the uniqueness of Canada and its traditions,” Justin Vovk, a Canadian royal historian, told the BBC – “a theatrical display that is meant to show what makes Canadians separate from Americans” and not, as Trump has often repeated, a “51st state”.

Both countries are former British colonies, but America’s founding fathers took a different path and severed all formal connections to the Crown nearly 250 years ago.

Canada’s separation from the monarchy has been more gradual, and its ties have never been completely broken. Canada’s parliamentary system is modelled after Britain’s Westminster system. The British monarch is still formally the head of state, but their duties are often carried out by their Canadian representative, called the governor general.

Loyalty to the Crown was seen as important to Canada’s politicians in the 19th Century who wanted to maintain separation from the US, said Canadian royal historian and commentator Carolyn Harris.

That later changed in the 1960s, as Quebec – Canada’s majority French-speaking province – began to assert its own distinct identity and threatened separation. This led to an era of politicians like Lester B Pearson and Pierre Elliott Trudeau who worked to untangle Canada from its British colonial past.

In 1982, Prime Minister Pierre Trudeau repatriated Canada’s constitution, giving full legislative power to the federal government and the provinces, and removing it from British parliament.

Ms Harris noted that Canada remained a constitutional monarchy throughout these periods. What fluctuated, however, was how much the prime minister of the day chooses to embrace that connection.

“We are devastated by the loss of our co-founder, colleagues and friends,” a spokesman for Sound Talent Group said in a statement to the BBC. “Our hearts go out to their families and to everyone impacted by today’s tragedy. Thank you so much for respecting their privacy at this time.”

The company said it lost “three employees in the plane crash” including Shapiro. It did not identify the others.

San Diego authorities confirmed at least two people were killed in the crash, though the National Transportation Safety Board – which is investigating the incident – said the total death toll is still unclear. Authorities have not released the names of any of those killed.

The plane, a Cessna 550 aircraft, veered into the neighbourhood around 3:45 local time (10:45 GMT). Such planes can carry up to 10 people, including a pilot, according to the Federal Aviation Administration.

In addition to his music career,  Shapiro was an avid pilot and a certified flight instructor with 15 years of experience, according to his aviation company Velocity Aviation.

Daniel Williams, who is thought to have also been on the plane, posted several Instagram stories in the hours before the crash. The posts showed him with Mr Shapiro and him sitting in the co-pilot seat next to the music executive, according to the San Diego Union-Tribune.

The post showed the flight number, which matched the one that crashed, the newspaper reported.