Sailors standing on the flight decks of Type 23 frigate HMS Lancaster and Type 45 destroyer HMS Dragon spelt out the word SISTER.
Both are Portsmouth-based ships which are currently deployed in the Atlantic.
HMS Lancaster, known as the ‘Queen’s Frigate’ sent their message of congratulations to her Her Majesty The Queen on the birth of her youngest great-grandchild.
Celebrations to mark the birth of the royal baby have been taking place not just in Bucklebury but all across the region. And she was widely admired for not letting sickness in the early weeks of he pregnancy carrying out a full programme of royal duties. We must warn you that Penny Silvester's report includes flashing images.
The Queen will be at Windor today presenting new colours to the Welsh Guards. her Majesty will then be join by the Duke of Edinburge and Duke and Duchess of Cornwall at a Regimental garden party in the grounds of the castle.
The Queen smiled warmly as she was presented with a bunch of daffodils at an Easter Sunday service.
She was dressed in a vibrant blue coat and hat at the service at St George's Chapel at Windsor Castle in Berkshire.
Family members, including the Duke of Edinburgh, Duke of York, Princess Royal and Earl of Wessex, joined the Queen at the service.
Lady Louise Windsor, the Countess of Wessex, Autumn Phillips and Princess Beatrice were also there.
Dramatic video of Prince Harry flying a Spitfire over the Isle of Wight. His instructor took over for the loop-the-loop.
Prince Harry flies a Spitfire - and puts it through a dramatic roll - as he visited the Boultbee Flight Academy in West SussexRead the full story ›
The shamrock is a symbol of the lucky Irish - but the Duchess of Cambridge had a spot of bother when she struggled to pin the sprig to an army mascot dog in Hampshire. Kate, 33, presented the bunches of clovers to soldiers from the Irish Guards to mark St Patrick's Day.
But as she bent down to pin the sprig on the silver collar of the regiment's beloved mascot, Irish wolfhound Domhnall, it kept falling off. Quartermaster Major Paul Fagin had to step in to give the royal a hand at the ceremony in Mons Barracks, Aldershot.
The dog handler Drummer Dean Kirk said:
"It wouldn't go on his collar, we had a bit of trouble with the shamrock. The shamrock fell off."
Kate later joked about the mishap with three children who presented her with a posy of white flowers. She told eight year-old Ciara Flynn and her twin sisters Leah and Eva, both six, that it was tricky. The girls' mother Mrs Flynn, 41, whose husband Mark is company sergeant major of the regiment, said: "She spoke about giving the dog the shamrock, and said it didn't stay on for very long."
The three year-old dog, who weighs 73kg, the equivalent of 11-and-a-half stone, was treated to a sip of Guinness after the ceremony. Kate, who is due to give birth next month, beamed as she arrived at the ceremony with the Duke of Cambridge. She covered her baby bump in a chic brown coat by Catherine Walker and wore a matching brown hat by Lock & Co.
Pinned to her coat was the gold shamrock brooch which was originally presented by the Irish Guards to the Queen Mother - who traditionally led the ceremony when she was alive.
William, 32, attended the traditional parade as Colonel of the Regiment and wore a navy blue frock coat. The couple spent around an hour at the parade and chatting happily to soldiers and their families afterwards.
The Duchess of Cambridge has been handing out sprigs of shamrock to soldiers in Aldershot to mark St Patrick's Day. It's believed it will be her last official engagement before she has her second child.
The Queen is to unveil the new 3.5 million visitor centre at the Battle of Britain Memorial at Capel-le-Ferne in Kent.
The site is the national memorial to The Few and the new centre will house an audio-visual experience to guide visitors through the story of the Battle in 1940.
The Queen and The Duke of Edinburgh will tour the new building during a 45-minute visit to the cliff top site on March 26. Pupils from Capel-le-Ferne Primary School will be completing worksheets on the Battle of Britain. They will also meet some of the last remaining members of ''The Few'', the pilots and aircrew fought who put paid to any plan for an enemy invasion by defeating the Luftwaffe in dogfights high above the skies of Kent and Sussex.
There will be will be a flypast by a Spitfire, Hurricane and Typhoon, which The Queen will watch from the balcony of the new Cockpit Café.
Their Royal Highnesses, The Duke and Duchess of Cambridge are the guests of honour at this year's Irish Guards' St Patrick's Day Parade in Aldershot.
Her Royal Highness will once again present the traditional sprigs of shamrock to the Officers and Guardsmen on Tuesday 17th 200 soldiers will march on to the parade square at their base, Mons Barracks marching behind the Band of the Irish Guards; they will, of course, be accompanied by Domhnall their Irish Wolf Hound regimental mascot, who will receive his own sprig of shamrock from the Duchess.
This is her last public engagement for the duchess prior to the birth of her second child.