Royal correspondent, BBC News
Princes William and Harry are to get a joint "household" - which means much more than a new office and their own ciphers.
It is a symbolic step and another significant one for two princes who are slowly, very slowly, establishing a presence of their own.
Their office, or household as it is called in royal circles, is based in St James's Palace. It reflects, said one aide, "their increased independence".
When you are a prince setting up an office, it does not just involve the positioning of pot plants or choosing where to place an Old Master borrowed from your grandmother's collection.
Following on from their coats of arms, which they acquired when they turned 18, Prince William and Prince Harry are now using their own ciphers in public on letterheads and formal documents.
The red in William's is the same colour as used by the Queen and his father, the Prince of Wales.
The blue in Harry's cipher is similar to the colour used by his mother, Diana, Princess of Wales.
This move is all about preparing the brothers for the future.
The present is sorted. For the next few years, their military careers will dominate their lives.
Both are about to undertake new challenges. William is poised to begin training to become an RAF search and rescue pilot.
Harry will also take to the skies when he starts learning how to fly helicopters with the Army Air Corps.
But what will occupy them in five years' time?
In William's case, especially, it is highly likely that by then his focus will be on working as a full-time member of a royal family whose octogenarian head will have recently celebrated her Diamond Jubilee.
His office has been set up to plan for this eventuality. Rather like the bride whom he will one day escort down the aisle, William's household has something old and something new.
Jamie Lowther-Pinkerton, a former SAS officer, will continue to work as Prince William's and Prince Harry's private secretary.
They have their own press officer, Miguel Head, who was described in one broadsheet as "an astute media adviser".
And to complement Mr Lowther-Pinkerton's military background, a former senior diplomat has been drafted in.
Sir David Manning was British ambassador in Washington and Tony Blair's foreign policy adviser in the run up to the Iraq war.
The former key aide to a prime minister is now destined to advise a future King.
For now though, it is a part-time role - he will be on call rather than sitting behind a desk.
He will offer advice, for free, when needed. In the short-term, Sir David might get involved if Prince Harry was to be deployed once again abroad.
In the longer term, he could be consulted on constitutional matters or possible overseas tours.
The guiding hand behind this appointment was the Queen. She has always taken a keen interest in preparing her heir's children, particularly William, for what lies ahead.
Her inspiration was her own experience as a princess. Back in the late 1940s, when occupying the throne seemed a distant prospect, she was advised by General Sir Frederick Browning.
"Boy" Browning, as he was known, was a war hero who had survived the Battle of Arnhem.
The Queen's idea is now a reality. William and Harry have their own household, ciphers and dedicated officials.
This much, and more, sets them apart from other twenty-something men.
But they do have at least one thing in common with their peers.
They have not left home. They still share their father's royal residences - and Prince Charles will foot the bill as his sons follow their new royal path.