The Princess of Wales introduced a new phase in her early years campaign at the National Portrait Gallery in London

Kate, the Princess of Wales, went back to school Tuesday, joining a group of young students on a field trip. The 43-year-old princess, a mother of three herself, surprised visitors outside the National Portrait Gallery in London when she stepped off a bus with a group of 4 and 5-year-old students from All Souls CE Primary School.

Kate Middleton made an official visit to the National Portrait Gallery today and arrived in a different kind of style. Instead of the usual convoy of royal vehicles, the Princess instead emerged from a bus alongside school children as they excitedly made their way to view a new project in the gallery.

The Princess of Wales hopped on a bus with schoolchildren for a "magical" excursion to the National Portrait Gallery in London

The Princess of Wales travelled by school minibus along with an enthusiastic group of five-year-olds, as she joined them on a visit to an exhibition in central London. Rather than a formal entrance in a royal car,