Greenwich has joined an exclusive group as the fourth local authority to become a royal borough and the first new one for more than 80 years.
The new legal status was made official with a Royal Charter signed by the Queen.
But what does it mean, why has it happened and what difference does it make?
Business Secretary Lord Mandelson announced in January 2010 that Greenwich would receive the accolade. He said it was in recognition of the close links between Greenwich and royalty since the Middle Ages.
He said the honour was also in recognition of "the borough's global significance as the home of the Prime Meridian, Greenwich Mean Time, and the Unesco World Heritage Site".
A new royal coat of arms can already be seen on some signs on the streets of the south-east London borough. It features a Tudor rose, for which special dispensation was granted, to represent the area's long association with royalty. New signs with the emblem will replace old ones as they wear out.
But how has Greenwich earned its royal stripes?
It is home to many former royal residences, including Eltham Palace, once a royal nursery for the use of Henry VII's children.
It also has several buildings with royal status including the Old Royal Naval College, built on the site of the old Greenwich Palace where Elizabeth I, Mary I and Henry VIII were born.
The new regal status is, in effect, similar to a person being awarded an honour, but far more exclusive, since the only others members of the club are Kensington and Chelsea, Windsor and Maidenhead, and Kingston-upon-Thames.
Chris Atkins, a librarian working for Royal Borough of Windsor and Maidenhead, said Windsor, as the home of Windsor Castle, so coveted the title that it actually took the name before it was officially received.
King George V allowed Windsor to be called a royal borough to "regularise a situation that already existed".
Kensington received its royal title after a wish left in the will of Queen Victoria who was born and brought up at Kensington Palace. Her son King Edward VII conferred the status in 1901.
Councillor Julie Mills, mayor of what became Kensington and Chelsea, said it was the "serene residential feel" and the use of the royal parks such as Kensington Gardens and Hyde Park, which made her royal borough different to others.
She admitted there was a historical tongue-in-cheek rivalry with Westminster which as a "City" borough is precluded from having royal status, despite being home to Buckingham Palace.
Asked if there was frustration that the borough's full title is rarely used colloquially, she said: "It's such a mouthful. These days we say K&C."
When Kingston first received its royal status in 1200 from King John it allowed the borough to collect its own taxes. Today people there see it as a mark of a proud history of links with the Crown.
The mayors of the four royal boroughs will meet later in the year to welcome Greenwich "into the fraternity" said Mrs Mills.
'Rare and exceptional'
Greenwich council has conceded that royal status does not provide any additional powers, resources or funding, but said it was a "very special honour" nonetheless, and would be used to "lever in further inward investment into the borough".
It has particular significance as it is one of the first actions to mark the year of the Queen's Diamond Jubilee.
It means that Greenwich will be the only royal borough among the six host boroughs for the London 2012 Olympic Games.
"Royal Greenwich is proud to take centre stage for this special year, which will create a legacy for local residents that will last for generations to come," said council leader Chris Roberts.
While other boroughs with royal links and without "City" status could potentially join royal ranks in the future, a spokesman for the Cabinet Office said: "The Royal Household has made clear that the grant of Royal Borough status to Greenwich in 2012 will be a very rare and exceptional mark of Royal favour."