Sarah Brown receives an ovation ahead of her introduction
Gordon Brown's wife Sarah stepped centre stage at the Labour conference to introduce his keynote speech.
The surprise move was seen as a break with tradition - and is a rare public address by Mrs Brown, who usually keeps a low profile.
She said she was "so proud" of her husband's achievements and praised his "motivation" to help people.
A visibly touched Mr Brown returned the compliment - but vowed he would never use his children as media "props".
Mr Brown had been due to be introduced by Dianne Hayter, who chairs Labour's ruling National Executive Committee, but Mrs Brown apparently suggested, the night before, that she introduce him instead.
She told delegates she had "asked if I could have the chance today to talk briefly to you" ahead of what was seen as a crucial speech for Mr Brown - who has faced calls for a leadership challenge.
Mrs Brown thanked delegates for the "warm welcome" they gave the couple after their wedding in 2000.
After a lengthy ovation, she introduced a video of key Labour achievements, telling delegates: "One of the privileges of my life over recent years has been the opportunity to meet so many different and extraordinary people.
"These have all been great moments, often private ones, but always meaningful and I thank you all."
Of her husband, she said: "I'm so proud that every day I see him motivated to work for the best interests of people all around the country.
"Sometimes in a world where there is so much to do we don't perhaps have enough time to celebrate what has been done."
She went on to introduce Mr Brown, "my husband, the leader of the Labour Party, your prime minister" - who made mention in his own speech about critics of his personal style, amid poor opinion poll ratings for Labour and rebel calls for a leadership challenge.
Mr Brown walked on stage to the strains of (Your Love Keeps on Lifting Me) Higher and Higher, by Jackie Wilson.
After spending several minutes trying to calm the cheering crowd down, he joked: "Thank goodness Sarah and I are a team," adding: "I am very proud to be her husband".
In the speech, he said he had not got into politics to be a celebrity and told delegates: "Some people have been asking why I haven't served my children up for spreads in the papers. And my answer is simple. My children aren't props; they're people."
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