By SARAH FITZMAURICE
Fairytale Princess: Emma Watson looked stunning in her Oscar De La Renta gown as she took to the red carpet
The crowds have been gathering for days, and the red carpet was ready and waiting for the cast of Harry Potter to premiere their final film.
And fans certainly were not left disappointed when Emma Watson arrived looking simply magical.
The 21-year-old actress brought the glamour in a floor length tiered Oscar De La Renta ruffled gown, a dress that made her look like a fairytale Princess.
Leading lady: Emma Watson played to the crowd as she posed for pictures on the red carpet
But her smiles didn't last long as Emma as she and many of her co-stars broke down while paying tribute to the final film in the franchise.
The actress welled up as her co-stars Daniel Radcliffe and Rupert Grint thanked fans and each other.
As Rupert took to his turn to speak Emma couldn't contain her tears and the film's producer David Heyman offered her his shoulder to cry on.
Tearful: Emma couldn't help but break down as other cast members spoke about the film
As Rupert pays tribute to the author Emma can't help but break down in tears and is comforted by the film's producer, David Heyman
Touching scene: The tearful actress was also comforted by Rupert and she rested her head on his shoulder
She clung onto him and in turn he gave her an affectionate kiss on the head, proving just how close the cast and crew members have become.
Earlier the scene was very different and shortly after Emma's arrival on the red carpet Harry Potter himself, Daniel Radcliffe, appeared looking dapper in grey suit and appeared to be overwhelmed by the response of the crowd.
Final call: The three main stars of the Harry Potter films, pose together for the final time on the red carpet
Setting the scene: Fans in Trafalgar Square could watch all the action live on a big screen and the famous trio also posed together on the top of the steps in full view of the crowds
In demand: Emma posed for pictures in her ice blue gown while crowds watched on
Speaking with his co-stars Daniel said: 'I don't think the end of the story happens tonight because each and every person who will see this film will carry this story with them through the rest of their lives.'
'A huge thank-you to all of you, first of all for giving me a job, and Jo for letting him give me a job.'
'Every opportunity I get from now on all goes down to the fact I got very, very lucky when I was eleven.'
Man of the moment: Daniel Radcliffe arrived on the red carpet after Emma to cheers by fans
Soaking it all in: Harry made his way up the stairs and seemed captivated by the sheer number of fans who had gathered in Trafalgar Sqaure
But Emma told him: You didn't 'get lucky' - you were and are the perfect Harry and will be forever.'
The actress broke down in tears as she said her thanks and was comforted by fellow cast members and by the author JK Rowling.
The third member of the wizarding trio Rupert Grint was the first cast member to arrive and fans were heard chanting his character's name 'Ron' in unison.
First arrivals: Rupert Grint was the first cast member to arrived followed shortly after by Tom Felton and his girlfriend Jade Olivia
It hasn't really sunk in: Rupert has said he can't believe that the Harry Potter franchise has come to an end
Say cheese: Rupert's fans seemed desperate to get a snap of him and he was happy to obliged
Rupert was also feeling emotional but thanked the author for what she had done 'for ginger people'.
The actor, who plays Ron Weasley arrived on the red carpet first and was followed by a bronzed Tom Felton and his beautiful girlfriend Jade Olivia who wowed in a flowing white gown.
As Rupert took in the screaming crowds, many of whom have travelled from around the globe to be part of the magic tonight he spoke about how he was feeling now the franchise has come to and end.
The woman who started it all: Jk Rowling was feeling floral as she took to the red carpet in a green gown with pink flowers for the final premiere of Harry Potter
Laughter and tears: The author also became extremely emotional as Emma's was torn between shedding a tear and laughing
Speaking to the BBC he said: 'It's hard to really believe. It hasn't really sunk in. It's unreal. It's so overwhelming. It's really strange.'
He added:'These last few months I've been in a bit of denial, I think, accepting the fact that it really is over. When I saw the posters in capital letters, "It all ends", it really does imprint that on the mind. I will miss this. It's been amazing.'
Stellar lineup: Alan Rickman and Timothy Spall made their way down the red carpet
Evanna Lynch who plays Luna Lovegood and Clemence Posy opted for short white dresses with the French actress opting for a ruffled number with a black waistband while Evanna wore lace.
Final call: Evanna Lynch looked looked great in a short cream dress and Matt Lewis was looking dapper
Fashion forward: Clemency Posy and Helena Bonham Carter stepped out in two very different looks
Red carpet veterans: Helen McRory Michael Gambon and Julie Walters
And it wasn't just the moment for the young ones, the film's senior actress and actors were also in high demand on the red carpet.
Ralph Fiennes charmed the crowds couldn’t have appeared less threatening, a stark contrast to his terrifying on-screen character Voldermort.
Helen McRory looked stunning in scarlet while Michael Gambon and Julie Walters showed off their skills interacting with the crowd.
Potter Pandemonium: Trafalgar Square has turned into camp Potter with thousands of fans gathered to catch a glimpse of the stars of the film
Dynamic duo: James Phelps and Oliver Phelps who play the Weasley twins strike a pose for the cameras
Pleased fans: Tom, who plays Harry's arch-nemesis Draco Malfoy pleased screaming girls by signing autographs
Proud brood: Warwick Davis and his family walk the red carpet
And there was no shortage of celebrity fans in attendance on the red carpet either.
The Saturdays Mollie King looked stunning as she arrived in a short dress with a flowing train.
The singer was joined by sisters Peaches and PIxie Geldof who were also dressed to impress for the occasion.
Footballer john terry and his wife Toni were all smiles as they made their way into the film.
Getting into character: Fans dressed up as their famous characters here Ellie Coote, 15, from Oxford, dressed as Professor Dumbledore clutches a book under an umbrella in the rain
Wet weather: Fans weren't put off by the rain and many queued without umbrellas to ensure they did not loose their spot
Guy Ritchie was also in Trafalgar Square with his pregnant girlfriend Jacqui Ainsley.
Fans of the Potter franchise have been camped out in Trafalgar Square for days and many got into character for the final send off.
Last night many members of the cast had gathered for a photocall and once again Emma Watson had wowed in a super short black dress.
Female fans: Pixie and Peaches Geldof arrived at the same time as Mollie King from The Saturdays
The former Burberry model has said she felt under pressure to make sure it was worth waiting for.
She said: ‘We've been building tension to this moment for like eight movies.
Happy families: John and Toni Terri and Guy Ritchie and his pregnant girlfriend Jacqui, who was showing off her baby bump seemed excited before the film
‘We were like, “People have been really waiting for this moment, and we have really got to pull this off.” And I was like “yes, I know. What are we going to do?”’
But she admitted that she thinks that she and her co-star ‘did alright’ on the smooching front.
The Harry Potter premiere red carpet event Emma Watson Video 2
Emma Watson Arrives at Trafalgar Square