Kate checked out of hospital today after a three-night stay interrupted only by a prank call from an Australian radio station.

As she stepped into a waiting car, clutching a bouquet of yellow flowers with her husband by her side, the Duchess told reporters in reply to their shouted questions, "I'm feeling much better, thank you."

St James's Palace released a short statement saying: "The Duchess of Cambridge has been discharged from the King Edward VII Hospital and will now head to Kensington Palace for a period of rest.‬‪ "Their Royal Highnesses would like to thank the staff at the hospital for the care and treatment The Duchess has received.”

In yet another break with royal tradition, Prince William has been spending every spare minute by his wife's bedside over the past few days of her hospitilisation. He arrived back at King Edward hospital this morning shortly after 9am (presumably just after she had been 'freshened up').

It's quite a different attitude to his father, Prince Charles, who spent just 17 minutes with a young William when he was treated for a head injury as a schoolboy before going to the opera.

But over the next few days the young royal couple will have to face up to the fact that they are  probably going to spend a large chunk of her pregnancy separated. Kate is expected to stay in London to be near doctors because the condition that the duchess, who is believed to be only eight weeks pregnant, has been diagnosed with can last for the first five months of pregnancy and  sometimes  for the  duration. William is obliged to return to his RAF base in Anglesey in Wales to make up his flying hours, which were severely impacted by the amount of time he had to take off work for the diamond jubilee celebrations. He is currently understood to be on compassionate leave.

A third night in hospital for Kate tonight, but the tedium was relieved by a visit from brother James and sister Pippa. The two siblings stayed for just under an hour.

Mel Greig and her sidekick Michael Christian, the two Australian radio presenters who made the prank call to Kate Middleton’s hospital with Greig pretending to be the queen, are both recent hires by the radio station 2DayFM which broadcast the call.

Michael Christian joined the Hot30 show just a few days ago, after labouring for several years in relative obscurity presenting a breakfast show on a  local Melbourne channel, and Greig herself has only been a host on the radio show since March last year.

They have issued an apology, of sorts, following a furore which erupted in the UK following broadcast of the call, with Prince William very much not amused by the breach of his wife’s medical privacy. The duo said in a statement: ‘We were very surprised that our call was put through. We thought we'd be hung up on as soon as they heard our terrible accents. We're very sorry if we've caused any issues.’

Chalk this up as the first security breach of the young royal's life.

A pair of Australian radio DJ's impersonating the queen and Prince Charles - and to the accompaniment of some unconvincing corgi sound effects in the background - rang the hospital in which Kate Middleton is being treated and were given an update on her condition.

Mel Greig and Michael Christian, who present the Summer 30 show on Australian radio station 2Day FM, called the hospital in the early hours of this morning.

The change in British law allowing for the first-born of William and Kate to accede to the throne regardless of sex will be rushed through Parliament in the new year, Nick Clegg, the deputy prime minister, said in the Houses of Parliament in London yesterday.

He said that by “wonderful coincidence” the final formal consents from other Commonwealth realms were received just as the Duke and Duchess of Cambridge revealed that they are expecting their first child.

Mr. Clegg said it was “a historic moment for our country and our monarchy.”

Newsflash! Kate's feeling better - but she's going to be staying in hospital for a few more days anyway.

After spending the day by his wife's side, Prince William has just left the London hospital where Kate will tonight spend a second night, with acute morning sickness.

Nort leaving were the hundreds of news reporters, photographer and TV crews who have set up camp outside the hospital in freezing conditions.

A St. James's Palace spokesman said tonight: "The Duchess of Cambridge is continuing to feel better. She and the Duke are immensely grateful for the good wishes they have received. She will remain in hospital at present and will continue to be treated for Hyperemesis Gravidarum.'

The writer Zoe Williams has penned a fantastic piece for the republican Guardian on 10 things she doesn't want to read about Kate's pregnancy. Her pet hates include pieces on what she should or shouldn't be eating, anything at all about their sex life, specualtion on when Pippa will get pregnant and anything that mistakes HG for 'bad morning sickness" which she says is like calling penumonia a 'bad cold'.

She also adds that she doesn't want to read an article headlined, "dilatey-Katie".

Prince William has just arrived back at King Edward Hospital to be at Kate's bedside, and didn't make a comment to waiting press.

Pregnant Kate Middleton is spending a second day in hospital today - Wiliam arrived earlier and the Middletons have left their home and are believed to be on the way -  and there is a mass of speculation in the British papers that Kate could produce twins, on the basis that hyperemesis gravidarum (HG) - the acute form of morning sickness from which Kate is suffering – is more common in mothers to-be who will have a multiple birth than other women (it’s also, as Dr Kent Sepkowitz explains on the Beast, more likely to occur in cases where the developing fetus is a girl).

But what no-one on the British press seems to have yet latched on to is the fact that  twins often run in families, and Kate and William’s bloodlines are stuffed full of twins. In fact many would see a family line of twins as a stronger predictor than HG.

As Robert Lacey wrote for the Royalist earlier this year, “Kate could very easily produce twins: William's uncle Charles Spencer has identical twin daughters; his grandfather Lord Fermoy was an identical twin; on Kate's side her paternal grandmother had a twin sister (Peter Middleton, Kate's grandfather, rather charmingly married one twin while his brother married the other) and Kate's father Michael had twin Middleton great-aunts.”

 Next Question: Where will Kate send Its Royal Babyness to school?

Gone are the days when royal children were educated by governesses in chilly royal schoolrooms, and William and Kate will be keen to get their kids signed up for one of the best London schools

Competition is famously intense for London’s best schools, but we don’t think the royal nipper will suffer the fate of Madonna’s son Rocco who was summarily turned down from fancy kindergarten Acorn.

The refurbishment of apartment 1A in Kensington Palace – the former residence of Princess Margaret – is almost complete, royal sources say, and there now seems little doubt that William will indeed quit the RAF next year allowing the couple to set up home full time in London.

Poor love.

It can't be much fun being Kate right now, especially as she is all alone.

Prince William has left his wife's side for the evening.

He was filmed coming out of the hospital shortly after 8pm.

Barack Obama, congratulated the royal couple via a White House spokesman: "On behalf of everyone here in the White House, beginning with the president and first lady, we extend our congratulations to the Duke and Duchess of Cambridge on the welcome news this morning out of London that they are expecting their first child."

David Cameron has revealed that when he was given the news of Kate's pregnancy today, he had to fight the urge to share the information.

Interviewed on TV he said: "It’s absolutely wonderful news, and I’m delighted for them and I’m sure they will make absolutely brilliant parents.

"I’m sure people round the country will be celebrating with them tonight."

"I got a little note came into a meeting I was having and I found it quite difficult to keep it to myself."