Many fans have turned up in costume for the book launch

Long lines formed outside bookshops all over the world, which opened at midnight BST to press copies of Harry Potter and the Deathly Hallows into the eager hands of children and adults alike.

BBC arts correspondent David Sillito joined one such queue at Waterstone's Piccadilly in central London.

He sent reports throughout the night as expectation built to fever pitch.

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Sorry not to have updated for a while, but I had a lot of TV work to do at midnight!

We had been expecting absolute bedlam but, in the end, the launch was remarkably controlled.

The first fans at the tills looked shattered. Most of them said the worst thing had been that, during the last couple of hours, people had been running up and shouting the end of the book at them.

They also said they would be very depressed when they reached the end of the novel and had no more Harry Potter left to look forward to.

I expect Childline's special Harry Potter counselling team will be getting a lot of calls in the next couple of days.

But there are already bets that there'll be another Harry book.

Could it be? No...

Picture sent in by Iona Mitchell

Only five minutes to go!

Street entertainers have been released to keep the fans entertained, along with public order officials from Waterstone's.

My favourite announcement of the night has been: "Please stand back from the mythical beasts".

The beasts are actually actors in outlandish costumes on stilts. The one nearest to me is called Brian, and he looks like a cross between a four-legged ostrich and Yoda from Star Wars.

We've also got magicians, and a seven-foot-tall Hagrid. The crowd around him is unbelievable. There's a definite look of fear in his eyes...

These pictures have just come in from Charmaine Mok, who passed the queue on her way home from work this evening.

"I'm not intending to join the queue," she says, "since I'm having my copy of the book delivered by tomorrow.

"But now that I've seen the fun and felt the atmosphere I kind of regret it! Here's hoping the postie comes dressed up tomorrow to honour the occasion!"

There's an essence of the blitz spirit at the front of the queue, where people have been taking it in turns to go off and have an hour's sleep.

By the time it reaches midnight, they will have been here for 58 hours...

The queue has turned into a "sea of bodies"

So far, I've been doing about two live reports into News 24 every hour, and a few bits and pieces for BBC World, too.

But the requests are starting to mount up as producers back in Television Centre gradually realise how many people there are here.

Generally, the presenters have been aghast at the sea of bodies, not to mention how they're dressed.

And don't forget that this isn't just happening in London - it's a global phenomenon.

The queue just keeps on growing!

Staff here at Waterstone's think it's going to take them at least three hours to sell books to everyone who has turned up.

Many of the fans have arrived in costume, which are just extraordinary.

One person has come as the Hogwarts castle. There's also a firebolt broomstick, three or four Dumbledores, one Dobby the house elf and probably approaching 800 assorted witches and wizards.

Have a look at some of the photos below - and if you're getting dressed up for the launch tonight, do send us your own pictures. Details of how to send them in are at the top of the page.

17-year-old Zoe (left) and 16-year-old Carina (right) from South London

Nadia, aged four, has come all the way from Mexico

These fans, dressed as owls, have been keeping the queue entertained with bird impressions

This is the fourth Harry Potter launch I've covered, and I've never seen anything like it.

There's between 1,000 and 1,500 people here. The queue stretches all the way around Waterstone's, which is Europe's largest bookshop, then spills out onto the street and continues as far as the eye can see.

Fans are revising the sixth book before they tackle number seven

And I think I've worked out why...

JK Rowling published the first Harry Potter book 10 years ago, when the core audience was about eight or nine years old.

Half of these kids are now 18, and they've just finished their A-level exams.

It's like the ultimate rite of passage. This is the end of childhood for thousands of people.

They're graduating with Harry.

The United Nations has arrived in Jermyn Street in Piccadilly.

In the space of just 20 yards, we have fans from Sweden, Mexico, Malaysia, the Lebanon, California, Finland and Reunion Island.

It's mind-boggling! I've only been able to find a few dozen people from Britain.

Some of the people here have even learnt English from the Harry Potter books, because that's the language they come out in first.