Prince Philip and Prince Andrew are believed to have a close and pleasant relationship with each other. But despite their closeness, the Duke of Edinburgh gave his second son a surprisingly bossy nickname.

In his book “Andrew: The Playboy Prince,” royal author Andrew Morton claimed that Prince Philip used to call Prince Andrew “The Boss.” This is because the Duke of York was the boss of the royal family.

“On a chilly February afternoon, the young man Prince Philip called ‘The Boss’ came bouncing into the world. His arrival heralded the start of the Queen’s second family – a source of great joy and pleasure to her,” Morton said.

When Prince Andrew got older, he started giving his mom, Queen Elizabeth II, her own nickname. The dad of two reportedly called Her Majesty “mamba,” but the moniker was not solely hers. The monarch shared the nickname with Prince Andrew’s nanny Mabel Anderson.

Morton didn’t reveal exactly how Prince Andrew came up with the unique nickname for his mom and his nanny. But the royal expert said that Prince Andrew used to be very close to Anderson.

Whenever Prince Philip and the Queen weren’t around, Anderson served as Prince Andrew’s constant companion.

“So closely did she guard her charge that when Prince Philip and the Queen went to Windsor for weekends they left baby Andrew behind rather than disturb the nursery routine. The Queen looked forward to Mabel’s night off with relish… For then she could go to the nursery and bath and read stories to her favorite son,” Morton said.

Meanwhile, Prince Andrew also made headlines recently after it was revealed that he is the Queen’s favorite child. Royal historian Piers Brendon said in the documentary “Paxman on the Queen’s Children” that the Duke of York was the Queen’s favorite son because he was hard working and heroic during the Falklands War. And as such, she has a soft spot for him.

Queen Elizabeth II Prince Philip Prince Andrew and Prince Edward
Pictured: Prince Harry, Prince Andrew, Queen Elizabeth II, Prince Philip and Prince Andrew watch the flypast over The Mall of British and US World War II aircraft from the Buckingham Palace balcony on National Commemoration Day July 10, 2005 in London. Getty Images/Daniel Berehulak