Kate Middleton
Kate Middleton makes a surprise visit to Amnesty International. Pictured: Middleton visits the Reach Academy with Place2Be on Jan. 10, 2018 in London. Getty Images/Eddie Mulholland

Kate Middleton is not slowing down when it comes to her royal duties.

On Thursday, the Duchess of Cambridge made a surprise visit to Amnesty International U.K. office. At that time, a conference on young people's mental health was being held. Middleton is an active mental health advocate and was there to support her patronage for the Anna Freud Centre charity that was co-hosting the Head Start conference, Hello! reported.

The charity shared some photos of Middleton's visit on Twitter. The organization was very pleased with the duchess surprise attendance at the event. One snap featured Middleton shaking hands with the organizers.

"We are delighted to welcome our Patron HRH the Duchess of Cambridge to the #HeadStartLearning Conference. HRH is a committed champion of children's mental health and wellbeing and it is fantastic to have her here," the caption read.

Another photo featured the Duchess of Cambridge talking with a young people and the staff leading the National Lottery funded HeadStart program. The program aims to build mental health and resilience in children and young people in the country.

Middleton's visit to Amnesty International was unannounced. It happened a day after she visited Reach Academy in Feltham. Middleton visited the school as royal patron of Place2Be. During her visit, she joined the children in their art activities. She also met and talked with the students who showed her Bear, the school trained therapy dog.

For the said sighting, Middleton recycled her floral printed Seraphine maternal dress. The wardrobe is among her favorites especially when she's pregnant. Middleton had been seen in it when she was still expecting Princess Charlotte in 2015.

The Duchess of Cambridge is known to rewear her outfits. In fact, in their family portrait for their Christmas card, she opted to rewear her Catherine Walker pale blue suit. Middleton first wore it in her first solo overseas in the Netherlands.

She wore it when she met King Willem-Alexander at Villa Eikenhorst. Middleton was seen in the same dress when she attended Camilla Parker-Bowles 70th birthday in July.

Just days before Middleton's birthday she was spotted walking her way to St. Mary Magdalene Church with Prince William and Prince Charles. In the said sighting, Middleton also recycled her coat, hat and gloves.