Crowds outside palace far thicker than a normal sunny Monday during school holidays. One policeman says he has been called in from his usual beat in Enfield.
By my rough calculation, I'd say there was close to 1000 people outside the gates and around the Victoria memorial. But the great majority are here for changing of the guard, not any royal baby announcement.
Mateo Martino, 23, from Uruguay is fairly typical when asked about the impending announcement. "If I see it, it will be interesting. But it's not a big deal for us."
11.05 David Cameron has also been offering words of support to the Duke and Duchess. He told the BBC:
Best wishes to them, a very exciting occasion and the whole country is excited with them. So, everyone's hoping for the best.
Best wishes to them, a very exciting occasion and the whole country is excited with them. So, everyone's hoping for the best.
Speaking later on BBC Radio 4's Woman's Hour he said had been "pretty involved" in the birth of his children.
It's up to every family to work out how they want to do these things.
I can't claim any role in this one, I'm afraid, except one small thing - well, it's a big thing actually - which is to get all of the heads of the realms over which our Queen is Queen, to agree that whatever the sex of the baby that Will and Kate have, if it's a girl, it will be our Queen.
A man puts out a rope barrier outside Buckingham Palace in central London, as well-wishers began to gather ahead of the birth of the royal baby. Photo: PA
10.55 Telegraph sketchwriter Michael Deacon is following the rolling TV coverage of the scene outside the Lindo wing of St Mary's:
Jovial BBC News reporter Simon McCoy, standing outside the Lindo wing, is doing a sterling job.
Jovial BBC News reporter Simon McCoy, standing outside the Lindo wing, is doing a sterling job.
"Plenty more to come from here, none of it news of course, but that won't stop us... Let's speculate, because that's all we can do... The world's media is gathered here to report the news that there is no news..."
Prediction: by the end of today, the man will be a national treasure.
10.45 The Duchess of Cambridge should expect to be in labour for around half a day, experts have said.
Consultant obstetrician Patrick O'Brien said that the average length of labour for a first-time mother is about 12 hours.
So the royal baby could be born in the late afternoon or early evening.
"About 12 hours is the average, sometimes quicker, sometimes slower, but that's what you have to budget for," he said.
The average weight of a baby born around its due date is 3.7 kilos (8.2lbs), he added.
"What's more important than weight is if a baby has been growing normally. We really don't mind whether babies are big or small or average, but we want to see that babies are growing along their own lines," he said.
10.35 The Archbishop of Canterbury has tweeted his support for the Duke and Duchess:
When the Duchess of Cambridge’s baby is born, it will be the first time in history that three generations of direct heirs will be in waiting while the sitting sovereign is fit and well. Photo: PA
10.30 Want to have your say on whether the royal baby will be a girl or a boy? Vote here in our poll:
10.20 Gordon Rayner's received news that the Duchess may have gone into labour earlier than previously thought:
10.10 The Telegraph's Spain correspondent Fiona Govan reports on the growing excitement on the Continent:
In Spain, where the Duke and Duchess of Cambridge are refered to as Guillermo and Catalina, there is speculation over the possible name of the new baby.
In Spain, where the Duke and Duchess of Cambridge are refered to as Guillermo and Catalina, there is speculation over the possible name of the new baby.
These too have been hispanicised - Could it be Jorge, Felipe or Alberto if a boy? Or possibly Alejandra, Carlota or Isabel, if a girl?
Spanish newspaper El Pais is also streaming live footage of the doors of St Mary's hospital, she says.
09.55 A bit of royal baby trivia:
The custom ended in 1948, with the birth of Prince Charles, but that didn't stop the Home Affairs Select Committee asking Theresa May whether she would attend this birth. She replied:
In fact, it is no longer the case that the HS is required to attend a royal birth.
Asked why the home secretary was once required to attend royal births, Mrs May said:
It goes back many centuries... the home secretary had to be there to evidence that it was genuinely a royal birth and that a baby hadn't been smuggled in.
09.45 Well-wishers from around the globe have begun to gather outsideBuckingham Palace. Tourists, armed with cameras, are peering hopefully through the Palace gates on the off-chance of spotting the easel, due to be placed on the forecourt detailing confirmation of the birth.
But there are plenty of royal fans from home soil too, including Terry Hutt, 78, from Cambridge, who's been camped outside the hospital for 12 days.
The former soldier, who served with the Royal Ordnance Corps, is sleeping on a bench across the road from the Lindo Wing.
"I have the best royal bed in town," he said. "I have lost my voice with all the excitement.
"At night we're watching the hospital in two-hour stints, like the Army.
"The health of the baby, and Kate, is the only important element."
Mr Hutt is wearing a Union flag suit and tie which a Dutch firm donated to him.
"My trousers are 10 inches too long," he said, adding that his wife of 51 years, Joy, thinks he is a bit mad.
09.35 Telegraph chief reporter Gordon Rayner tweets:
Members of the broadcast media give live reports across from St. Mary's Hospital.
09.20 More updates for the astrologers amongst us:
If the royal baby arrives today, its birthday will fall under the zodiac sign of Cancer, but if born very late this evening or tomorrow, it will be a Leo.
But one astrologer, Patrick Arundell, has predicted the baby will have a "very Cancerian personality" even if it is born under the sign of Leo.
He said the future king or queen would be more conventional if a Cancerian, but more of a groundbreaker if born tomorrow as a Leo.
"Either way, he or she is going to be larger than life, charismatic and glamorous but they will have a very Cancerian personality, whether under the sign of Leo or not, and be sensitive and caring," Mr Arundell said.
He added: "If the baby's born today it will have a slightly more conventional and conservative personality, but if it's born tomorrow it will be more groundbreaking and more in tune with modernity."
There is a heavy police presence outside the Lindo Wing of St Mary's hopsital. Photo: AP
09.15 Once the Duchess has had the baby, the next question on everyone's lips will be, when will get to see the new prince or princess?
09.00 As a quick aside, my rival royal baby live blogger over at the Guardian has made a bold declaration. He is a republican.
Peter Walker tweets:
I'm about to hand over this blog to my colleague, Paul Owen, while I'm being sent to join the media hordes at the hospital. Can I made a quick confession before the keyboard is wrestled from my hands? I'm a republican. But I nontheless, of course, wish all concerned the very best.
I should probably make my own declaration. I am not a republican.
08.50 Dickie Arbiter, a former press secretary to the Queen, remembers the scene at St Mary's more than three decades ago when William was born:
"I was here 31 years ago when William was born so we have come full circle," he said.
"You did not have 24-hour news in those days, though there was a very large media presence and the hospital across from the Lindo Wing was just a wall.
"The family will be waiting like any other family for news of the baby.
"The Queen will be the first to be informed because William will telephone her as soon as something happens.
He added: "William be at Kate's side comforting her. He will be as concerned as she is.
"She is going through the agony and he is sharing it.
"It is a new experience for every father and parent; he can be told about what details are like but she's experiencing it.
"The royals won't come down.
"Diana was in for 22 hours; she had the baby one day and left the next. Kate might do the same thing.
"The Middletons might come down but the royals won't because it demands another level of security and the last thing they'll want is to disrupt the hospital. It doesn't really warrant a visit."
Members of the world's media gather outside The Lindo Wing as The Duchess Of Cambridge goes into labour at St Mary's Hospital. Photo: Getty
08.45 The Duchess may have gone into labour, but there's still time to play the guessing game over the baby's name.
Bookmaker William Hall has reported George as the favourite for a boy and, after a flurry of bets, Alexandra - one of the Queen's middle names - as the favourite for a girl, while Charlotte is also thought to be a contender.
But with the name of the Duke and Duchess of Cambridge's first born likely to set a trend for the next generation of babies, the question is, what do you call a child who's name will be remembered for hundreds of years?
08.30 Meanwhile, the Press Association have been out interviewing some very excited royalists among the public.
Carly Gargett, 31, an event manager from Sydney, Australia, who lives in London, said: "I have been doing live Facebook updates to all my friends back in Australia.
"They were texting me this morning saying 'What's going on?' because I'd missed it happening so early.
"So I came down to the site on my way to work. I am a real royalist.
"I was at the Coronation Festival last week and was hoping she would go into labour then."
Miss Gargett said she thinks the Duchess would love to have a girl.
"Every girl would like a girl princess," she said.
"I'm picking Charlotte as the name - I have a feeling in my waters.
"I don't think I'll be doing a lot of work today, I have the royal baby cam live feed to my phone, I am so excited.
"And Kate is handling it all in such style as always - it can't be easy with the eyes of the world on her."
08.20 For those readers into astrology, our chief reporter Gordon Rayner is the man to follow:
08.15 Here is a look at the royal baby by numbers:
2 - Number of years the Duke and Duchess of Cambridge were married before the birth of their baby.
3 - William and Kate's baby will be born third in line to the throne and the Queen's third great-grandchild.
4 - The baby will bump Prince Harry down to fourth in line to the throne.
5 - William and Kate's first-born will be the great-great-great-great-great-grandchild (five greats) of Queen Victoria.
16 - The baby will one day be head of state of 16 countries.
31 - William and Kate will both be 31 when the baby is born.
41 - Royal births are celebrated with a 41-gun salute.
43 - If the baby follows the Prince of Wales and William on to the throne, he or she will be the 43rd monarch since William the Conqueror in 1066.
£6,265 - Cost of a one-night stay and delivery package at the private Lindo wing including a suite of two rooms, but excluding consultants' fees.
£19 million - The yearly income from the Duchy of Cornwall landed estate - which, when one day the baby becomes the heir apparent, will be used as its private funding.
Two billion - The baby may one day be head of the Commonwealth, which covers 54 nations and two billion citizens.
Police stand guard at the doors of The Lindo Wing as The Duchess Of Cambridge goes into labour at St Mary's Hospital.
08.10 Telegraph features writer Bryony Gordon, who has recently had a baby herself, hopes Kate's labour is slightly speedier than her own:
08.05 Of course, confirmation that the Duchess is in hospital also means the nation is aware that Kate is in labour.
This is something that would have been unthinkable when the last granddaughter-in-law of a reigning queen to give birth to a future monarch did so in the 1890s.
George V's wife Mary of Teck, who was then the Duchess of York, had the future Edward VIII in 1894 and the future George VI in 1895, but news of her 'confinement' was limited.
Dr Rowbotham, a social historian at Nottingham Trent University, said: "Pregnancy was not something that was publicly talked about then. It wasn't discussed. It was indelicate."
Members of the world's media gather outside The Lindo Wing as The Duchess Of Cambridge goes into labour at St Mary's Hospital. Photo: Getty
07.55 The world's press have been camped outside St Mary's in Paddington for days in anticipation of the birth, but excitement is likely to reach fever pitch now Kate's labour has befun.
Alistair Bruce OBE explains how the news of the royal birth will break - and when the public might get a first glimpse of the future king or queen.
07.50 The Kensington Palace statement announcing the Duchess had gone into labour was made at 7.30am but she was admitted to St Mary's around two hours ago, just before 6am.
Kate and William, who spent the weekend at Kensington Palace, travelled without a police escort, their spokesman said.
He added: "Things are progressing as normal."
07.45: Good morning, the Duchess of Cambridge has been admitted to St Mary's Hospital in London in the early stages of labour, Kensington Palace said today.
She travelled by car from Kensington Palace to the Lindo Wing of the hospital with the Duke of Cambridge.