Police formed a ring of steel around Wembley Stadium yesterday during a concert that grabbed global attention and was potentially a prime target for a terrorist assault.

Inside, the audience was taken back to a more innocent time. The girth of some of the stars might have been more ample, and the wrinkles a bit deeper, but it was possible for the music fans there to imagine that they were back in the days when a princess was jigging along to Duran Duran.

If an event organised by the second and third in line to the throne and featuring a stellar line-up was a headache for security chiefs, the fans were not going to let that spoil the party.

Prince William and Prince Harry sought to reclaim the image of their mother, Diana, Princess of Wales, with a concert — on what would have been her 46th birthday — to mark the tenth anniversary of her death. So, while some of their own favourite acts were on the bill, this was predominantly an event to reflect her personality and passions, from the English National Ballet to Bryan Ferry.

Those at the concert were keen to show that they were not deterred by the terrorist threat. “If we start changing the way we behave then they have won, haven’t they?” Pam Wright, 46 from Hatfield, said. “This is probably the safest place in the country today.”

As Sir Elton John opened the show at 4pm for an estimated worldwide television audience of 160 million, the stadium was only three-quarters full. There were still long queues while security guards frisked those entering the stadium with handheld metal detectors. Some seats remained empty throughout the show and it was not clear if these belonged to people who had been deterred by security concerns or to the touts who were not doing much business before the show started. About 500 police were in the area.

Asking the audience to have an “awesome” time, Prince William said that the concert was “about all that our mother loved in life — her music, her dancing, her charities and her family and friends”. But there was a reference to the troubles in the world as Prince Harry, who was prevented from joining his regiment in Iraq, said: “I would like to take this opportunity to say hi to all the guys in A Squadron of the Household Cavalry, who are serving out in Iraq at the moment. I wish I was there with you. I’m sorry I can’t be. But to all of those on operations at the moment, we’d both like to say — stay safe.”

Kate Middleton, the former girlfriend of Prince William, was among a group of the princes’ friends in the royal box that also included Chelsy Davy, Prince Harry’s girlfriend. Newspaper reports have claimed that the heir to the throne and Miss Middleton have rekindled their relationship, but Prince William had been coy when asked if she would be there, telling reporters: “I’ve got lots of friends coming. So everyone is going to be there.”

Miss Middleton sat a short distance from Prince William, and her family were also there.

Prince William had said that “it’ll be a terrifying sight” if he and his brother danced, but they tried gamely, displaying less style than their mother, perhaps, but rather more than their father. She famously danced along at Live Aid while Prince Charles looked somewhat uncomfortable.

The brothers introduced Duran Duran, their mother’s favourite band. John Taylor said that before the concert the brothers had told them to keep the tone of their performance “upbeat”. He added: “I thought it was very brave of them to put this show on. I can only imagine the emotions that there would be putting on this in remembrance.”

Many in the crowd said that they wanted to celebrate the Princess’s life. “I like a lot of the music but she was the reason I came,” Amanda Knight, 55, said. “I slept on The Mall the night before her funeral and I still think her life had a big impact. Hopefully her boys can continue her work and this concert shows that they know how to connect with people like she did.”

Proceeds from the concert will go to charities supported by the Princess and her sons. This was possibly the best-groomed audience of any rock concert. It was not a day for the mosh pit, it was day for eating strawberries and cream (£4 for ten strawberries) and remembering the days when one woman rocked all over the world.

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