Just two hours before the leader of the country was due on stage at the Labour conference she told him of her plan to introduce him personally on the platform.
"I'm so proud that every day I see him motivated to work for the best interests of people all around the country," said the 44-year-old mum of two. And Mr Brown was visibly moved as she wound up by introducing him as "my husband, the leader of the Labour Party, your prime minister".
Sarah, who usually prefers to stay out of the limelight, had awoken in the early hours of Tuesday morning convinced she was uniquely placed to persuade the public her husband is still the man for the top job. And the clarity and warmth of her speech - every word of which was her own - earned her a standing ovation from delegates.