Perhaps mindful too that her sophisticated friend Michelle Obama was attending, the 45-year-old had picked out three simple but super chic outfits.
The mother of two began the day in a black blazer and cream skirt, accompanied by her signature accessory - a set of bright beads - as she left Heathrow with husband Gordon Brown.
Before landing Sarah performed a quick change slipping into a dignified belted jacket and skirt appropriate for her audience with Pope Benedict at the Vatican along with the other G8 wives.
Her final - and most striking - ensemble consisted of a bold skirt featuring a vivid orange stripe and crisp white three-quarter length sleeve shirt.
Never one to lag behind in the fashion stakes, US first lady Michelle created an impact with just one dress – a dazzling canary yellow shift worn with a green corsage.
On Friday, France's picture-perfect premiere dame Carla Bruni-Sarkozy is set to show off her style credentials at the event.