11.17am:

It's official. There is to be a royal wedding next summer. Clarence House has today confirmed that Prince William and Kate Middleton are to marry. Here's the full statement:

The Prince of Wales is delighted to announce the engagement of Prince William to Miss Catherine Middleton. The wedding will take place in the Spring or Summer of 2011, in London. Further details about the wedding day will be announced in due course. Prince William and Miss Middleton became engaged in October during a private holiday in Kenya. Prince William has informed The Queen and other close members of his family. Prince William has also sought the permission of Miss Middleton's father. Following the marriage, the couple will live in north Wales, where Prince William will continue to serve with the Royal Air Force.

I'm sure you will all want to rejoice at the news in the comments section below. The moderators have been warned.

Before you all wade in with what will no doubt be robust views on whether we shoud live blog this announcement and its aftermath, the prospect of the wedding does raise some important questions:

• The wedding is likely to be a key test of feelings towards the monarchy since the last big royal wedding in 1981. How much has republican sentiment increased since then?

• Will the wedding itself change public opinion towards the royal family – positively or negatively?

• In the age of austerity and cutbacks who is going to pay for it and how much will it cost? Will it be an austerity wedding?

11.36am: Top marks to Ed Miliband for being one of the first to offer congratulations. He tweeted this a few minutes ago.

Delighted for Prince William and Kate Middleton on their engagement. The whole country will be wishing them every happiness.

He won't be the last.

11.49am: What will she wear? The Mail on Sunday has been researching this key question for some time.

It reports that her favourite designer is Daniella Issa Helayel. It quotes a friend: "She loves Issa's look and wears it well. Kate knows she's going to need conservative yet attractive outfits once they are engaged and she's started collecting a very enviable wardrobe."

Speaking to PA Peta Hunt, fashion director at You & Your Wedding magazine, has this crucial insight:

I can't see it will be covered in Swarovski crystals. I think it will be hand embroidered and I think with lace." She must have some sort of crown or tiara. I would imagine shoulders would be covered at some stage. I think a high neck would look fantastic. It's quite refined and could be quite stylish.

11.55am: Reams of pre-written copy is spewing out of PA, such as this



He reportedly calls her "Babykins", while he is apparently her "Big Willie".

12.00pm: Republicans are already complaining about the likely cost.

Here's Graham Smith, spokesman for Republic:

I'm sure this is very happy news for those who know the couple, but it is a private matter and we mustn't see the government wasting limited resources paying for a major set-piece event. William is not the head of state, there is no guarantee he will ever be head of state. This is a private occasion which I'm sure the palace will want to milk for maximum PR effect. It is not for the taxpayer to pay for any part of this event, the Windsors must cough up." Inevitably there will be additional security arrangements for the wedding, but that must be paid for by the Windsor family from their own personal fortunes, not by taxpayers who are experiencing sweeping spending cuts. If people are being told to tighten their belts, if the government is making thousands unemployed, if welfare payments are being slashed, it would be sickening for the government to allow a single penny more to be spent on the royals at this time. Spending public money on this wedding or affording it any special status would be no more appropriate than if it were Ed Miliband's wedding. This is a private occasion. We are certain the palace spin doctors will be working overtime to use this opportunity to their advantage. Republic today makes this pledge to do all it can to counter that PR campaign and continue to push the case for a modern and democratic institution in place of the monarchy.

That reads like something Republic made earlier. It is not just royal correspondents who have pre-written material on this.

12.08pm: A good day to bury bad/awkward news? According to Mirror's James Lyons David Cameron was told about the engagement, just before Downing Street announced that it would not be putting the PM's official photographer on the public payroll after all.

12.19pm: Royal wedding tat update, from my colleague Helen Pidd:

Just spoke a woman from Asda, who confirmed the supermarket is planning to flog as much memorabilia as possible - "because we all love a royal wedding, don't we?". She said Asda had already bought aline of Will n Kate mugs, and was unlikely to stop there. The supermarket has form when it comes to churning out Royal tat: in 2005, it sold a £19 replica of Camilla's engagement ring.

12.24pm: Get yourself a good pre-nup, Patrick Jephson, Princess Diana's former private secretary, advises Kate Middleton. He told PA:

There will be a tidal wave of sentimental slush, but you've got be practical. If she was my sister, I'd tell her to get a good pre-nup." This is no ordinary marriage and the last decade has had these terrible divorces.

12.29pm: The Clarence House Twitter stream is a bit slow off the mark but it got there three minutes ago.

The Prince of Wales is delighted to announce the engagement of Prince William to Miss Catherine Middleton.

Elsewhere on Twitter there appears to be an I'm Spartacus campaign to announce plans to blow up Buckingham Palace, in solidarity with the man convicted of threatening to blow up an airport in a joke on the network.

12.37pm: Will the government's happiness index be ready in time for the wedding? And if it is, will the royal wedding boost public morale or send us all into a tailspin of revulsion?

12.42pm: "It's great to have a bit of unadulterated good news," said David Cameron at a press conference on Downing Street.

It will be great day of national celebration, he said and told Prince William so in a phone call.

Cameron also revealed that as a boy he had slept on the side of the Mall waiting to see the Charles and Di wedding in 1981. Really?

12.48pm: Wills n' Kate, as they're known, are going to do photocall at St James Palace, at 4.45pm.

Don't expect any reruns of those "whatever-love-means" comments made by Prince Charles.

1.01pm: Kate Middleton is the first commoner to marry an heir presumptive to the throne in more than 350 years, writes Stephen Bates.

Among Middleton's ancestors are Northumbrian miners and Kent builders' labourers. Her mother, Carole, was formerly a British Airways flight attendant – hence the snobbish jibes of some royal hangers-on about "doors to manual" – and her father, Michael, also once worked for BA as a dispatcher, making sure flights left on time and with the correct cargo. The couple met while working for BA and started their married life in a flat in Slough, just across the river from the future in-laws.

But she is still pretty posh:



At Marlborough public school in Wiltshire, she became captain of the hockey club and gained a reputation for quiet seriousness, unlike some of her contemporaries. As Jessica Hays, one of her schoolfriends, told the News of the World wonderingly: "I never once saw her drunk. Even after our GCSEs finished, she only drank a couple of glugs of vodka."

Tom Bradby of ITV

1.10pm: ITN's Tom Bradby, an old friend of William's has secured the first interview. It will be broadcast this afternoon, Clarence House has announced.

Its head of press Miguel Head has also issued a mildly threatening warning to the media about the privacy of the happy couple:

We have a very good working relationship with all of you, but, if I may, I would also like to take this opportunity to remind everyone that the Middleton family remain private individuals. Particularly, may we ask you to remind your picture desks about PCC rules concerning the use of photographs that may have been taken following harassment or a breach of privacy. If you have any concerns about a photo, please refer your concerns to the PCC or to the Clarence House press office. Thank you in advance for your cooperation.

1.19pm: Alan Sugar, no less, thinks it's good day to bury bad news. He's been tweeting about little else in the last hour or so.

1.24pm: Hold the front page, Majesty magazine has been forced into a hasty redesign of its latest issue, according to Helen Pidd.

Majesty, which "gives its readers a colourful insight into the privileged lives of the royal families of the world", has had to make an eleventh hour change to its December

edition. The Queen was due to be the festive cover girl, but has been bumped for a shot of the happy couple, managing editor Joe Little told me.

1.28pm: Ladbrokes is offering odds of 1000-1 that Royal Wedding will take place in Vegas.

The favourite locations with Ladbrokes is Westminister Abbey at 11-8. St Paul's is second favourite at evens.

The smart money is going on St Paul's according to William Hill. "Since the announcement we have only seen money for St Paul's, which would suggest that that is the most likely venue," said Hill's spokesman Rupert Adams.

1.42pm: The Daily Mail won't like this. During the Pope's visit it was outraged that Labour activist and wife of the speaker Sally Bercow was sending out cheeky tweets about his holiness. Bercow has been in similarly irreverent form about today announcement.

When the prime minister said he had slept on the Mall the night before the Royal wedding she tweeted: "fancy admitting that".

She later quipped: Take heart all worried London housing benefit claimants - David Cameron slept rough on the Mall once.

1.50pm: William and Kate are following a familiar pattern for former students of St Andrews University.

A spokeswoman for the university said: "St Andrews is a special place – one in ten of our students meet their future partner here, and our title as Britain's top match-making university signifies so much that is good about this community."

Scotland's first minister Alex Salmond has also got in on the St Andrews angle.

"Of course this was a match made in St Andrews, and everyone in Scotland will join with me in wishing the Prince and Ms Middleton every happiness as they look forward to their wedding day, and a long and fulfilling married life together."

So much for his radical credentials.

2.02pm: There's much more on suspicions of burying bad news on Andy Sparrow's politics live blog. Number 10 insists that it did not hear about the engagement before slipping out that announcement about Cameron's vanity staff.

2.11pm: London mayor Boris Johnson is offering city hall as possible "cut price" venue

"If they want a cut-price deal with a central London venue with a view of London landmarks, the ideal place would be City Hall," he is quoted as saying in Docklands 24.

2.16pm: Aynsely China has sent us some images of wedding tat. Including this plate.

Royal wedding thimbles are also available on eBay for £2.

Photograph: Rex Features

2.31pm:

Prince Charles has issued a characteristically curmudgeonly response.

Speaking at his Poundbury model village in Dorset, he said: "thrilled, obviously, thank you. They have been practising long enough".

2.43pm: Charles hasn't changed much in 30 years, but what about the rest of us?

2.50pm: It's going to bring the world to a standstill, according to the Daily Mail.

(I can hardly wait. But right now I've got to pick my kids up from school. Thanks for all your comments. My colleague Mark Tran is itching to take over.)

3.04pm:

Thank you Matt, who can't wait to liveblog the event in all its world-stopping glory next year. Talking of tat, a quick scan of eBay shows you can pick up "Orig Press Photo Kate Middleton Princess Diana William" for $10. Will we see a run on such items in the days, weeks, months to come.

3.13pm:

In case William and Kate need an astrologer, one Russell Grant is offering his services. His energetic PR has sent out this email forwarded by my colleague Leo Hickman. It says:

Russell Grant is currently available for compatibility readings and forecasts on the best date for the wedding of Prince William and Kate Middleton, officially announced today. Russell was part of the BBC teams for the royal weddings of both Prince Charles and Prince Andrew, where he gave accurate predictions on the compatibility of both couples. Russell went on to become a close confidante of Princess Diana, becoming unofficially known as the 'Astrologer Royal' in the process. Former butler Paul Burrell said of Russell: "The only one (astrologer or psychic) she ever trusted was Russell Grant.

3.19pm:

More on the dress.

Elizabeth Emanuel, who designed the wedding dress for Diana complete with a 25ft train, 10,000 pearls and sequins, ivory silk, pure taffeta and lace, thinks Kate will wear a very different kind of dress. She tells PA:

I would imagine it would be very different to what Princess Diana wore because fashion changes so much. I think that what the bride will wear will be the big question that everyone will be asking. She has a great sense of style. A royal wedding is always fabulous. It's brilliant, isn't it? It's absolutely wonderful.



Meanwhile the British Fashion Council is hinting not so subtly that Kate should stick to British design: "We have the best emerging designers in the world here in the UK and the designer that she enlists to make her wedding dress will have a once in a life time opportunity to have their work seen by millions of people across the globe."

Helen Pidd. Photograph: Martin Argles/The Guardian

3.29pm:

My colleague Helen Pidd says the wax modelers at Madame Tussauds had better get a move on as they currently don't have a Kate Middleton figure. A spokesman told Helen, however that one is on the way. "We definitely plan to make one to go in the attraction after their marriage. We will be seeking a sitting with her in the near future." The Royals currently in London's Tussauds are Charles, Camilla, Harry, William, the Queen and Prince Phillip.

3.36pm:

The tourist authorities are salivating at the prospect of thousands - maybe millions even - of visitors descending upon Britain for the wedding of the century - yes we can do hyperboles too. Sandie Dawe, chief executive of VisitBritain, claims it will bring in lots of dosh. In a typical year, she claims, "the places, events and history associated with the monarchy generate well over £500m in revenue for the British tourism industry".

3.40pm:

Will there be a poem from poet laureate, Carol Ann Duffy, to mark the occasion? My colleague James Meikle reminds me that Andrew Motion wrote Spring Wedding when Charles and Diana got hitched.

3.42pm:

First reaction from Kate Middleton's parents. They are "absolutely delighted" and "thrilled". No Charles-like gracelessness there.

3.53pm:

The US press has swung into action. It's top story on People magazine and it's on the New York Times website, where its London correspondent, Sarah Lyall, writes in a chunky piece:

Interested parties can now focus on a new set of pressing issues: Who will design Kate's wedding dress? How massive will her engagement ring be? Who will be Prince Harry's date at the wedding? And, should Miss Middleton become queen – an event that would not take place until the death of both the current queen and the future king, Prince Charles -- will everyone call her "Queen Kate?" (Her name is actually Catherine.)

Surprisingly, nothing on the New York Post website yet.

3.59pm:

Here's the full statement from Kate's parents as read out by Michael Middleton outside their home near the Berkshire village of Bucklebury.

I would just like to say that Carole and I are absolutely delighted by today's announcement and thrilled at the prospect of a wedding some time next year. As you know Catherine and Prince William have been going out together for quite a number of years which has been great for us because we have got to know William very well. We all think he is wonderful and we are extremely fond of him. They make a lovely couple, they are great fun to be with, and we've had a lot of laughs together. We wish them every happiness for the future.

.

4.03pm:

Here's that remade front page of Majesty

4.09pm:

Diana's brother, Earl Spencer, who made that emotionally-charged speech at Diana's funeral at Westminster abbey, has added his congratulations. "It's wonderful news. Very exciting. My family are all thrilled for them both," he said.

The couple will give their first interview to ITV News's political editor Tom Bradby, an old friend of the prince, which will be broadcast at 7pm. They are due to appear before photographers at St James's Palace at 4.45pm. Expect lots of shots of the ring.

Michael White Photograph: Linda Nylind for the Guardian

4.28pm:

How should republicans react to next year's bash. Here's what my wise colleague Michael White suggests:

Republicans should see the royal wedding – the cost, the extravagance, the fawning – as an opportunity to expose the monarchical tinsel for the sham they believe it is. But snarling would be the wrong tone to adopt; not usually an effective educational tool. Good-natured laughter is better, but most of the ardent republicans I know tend not to see it as a laughing matter. Best to lie low and let it all wash over the event would be my unheroic advice, which I am confident will be ignored, thereby probably helping to boost monarchical sentiment.

4.33pm:

Who's winning the early media skirmishes? John Plunkett at Media Guardian gives the nod to ITN.

First blood – if that's not an entirely inappropriate phrase – goes to ITV News political editor Tom Bradby, who has bagged the first interview with the couple. It probably helped that he is an "old friend" of the prince. David Dimbleby remains the BBC's go-to man for this sort of thing, and at the risk of hastening his retirement – the very thought – a royal wedding would be quite a way for the Question Time presenter to sign off.

4.38pm:

Tom Bradby tweets that William has given Kate his mother's engagement ring.

4.47pm:

A quick search on Google yields these factoids on that ring. An oval blue sapphire ring from Garrard jewellers, it weighed in at an "astounding 18 carats", surrounded by 14 small diamonds in an "elegant cluster setting". At the time it cost £28,000.

4.53pm:

More reaction from the politicos. Nick Clegg, the leader of the Lib Dems, says "everyone will be united in delight and joy. On the British monarchy Facebook site, 4,928 "like" the announcement and counting.

4.58pm:

The cameras are popping like mad as the couple walk down the red carpet. Kate in a blue dress is wearing that sapphire ring. The photographers have been told to calm down the flashes. She is asked how William proposed. She goes "Aah, he's a true romantic." She is very poised and composed.

5.00pm:

The timing is right now, says William when asked why it took him so long. He says about the ring that it's very special and Kate is special too. it's my way of making sure my mother didn't miss out on today. Asked why they love each other, he says we have a fun time together. She's down to earth. She says he's very loving and very supportive in good times and bad times.

5.08pm:

Pretty assured performance from Kate Middleton on what must have been a daunting outing before the world's media. She came across as someone more at ease before the press than Diana when she made her first apperances before the press, but then they have had eight years to prepare for this day.

The Queen held a reception this afternoon at Windsor Castle for leaders of British overseas territories including Bermuda, Montserrat and the Falklands Islands. One of the guests congratulated her on William and Kate's engagement, to which she replied: "It is brilliant news. It has taken them a very long time."

5.23pm:

Now that they have appeared before photographers for the pictures that will be on all the front pages tomorrow, this seems an appropriate moment to end the live blog. Thank you for your many, many comments and here's a recap of the main points.

• Prince William and Kate Middleton are to marry next year. No date set yet.

• He gave her his mother's sapphire engagement ring

• Asked why now after an eight-year on-off relationship, William said: "The timing is right now, we are both very, very happy."

• Kate said: "Hopefully I'll take it in my stride."

• The Queen said: "It is brilliant news. It has taken them a very long time."

• The prince asked Kate to marry him during a private holiday in Kenya last month