The Duchess of Cambridge looks elegant in tweed during surprise visit to women's prison

Kate Middleton, the Duchess of Cambridge, looked effortlessly elegant this afternoon as she visited Send Women's Prison in Surrey. During the trip, which was conducted under initial secrecy for security reasons, Kate met with female prisoners who are involved in a program with The Rehabilitation of Addicted Prisoners Trust (RAPt), working on the road to recovery from drug and alcohol addictions. The female prisoners are said to have not known who was coming to visit until just an hour before Kate's arrival.

One of the Duchess's many passions, Kate has been interested in combatting addiction for some time now. She has worked with Action on Addiction since 2012, and is clearly taking a larger interest in the fight against a battle many face.

"Addictions lie at the heart of so many social issues," Duchess Kate said today, "substance misuse can play such a destructive role in vulnerable people's lives." She expressed her thanks to the women who shared their sometimes painful stories with her, and called on the need to intervene early in life to battle substance abuse.

"I am grateful to the women I met for sharing their difficult personal stories with me. It is encouraging to learn how organizations like RAPt are offering specialist support to help people break the cycle of addiction and look forward to a positive and crime free life."

For the visit today, Princess Charlotte and Prince George's mom looked elegant in gray from head-to-toe. She wore a silver tweed dress with a peplum accent by The Fold, which retails for about £365.00 ($550) and grey suede pumps by Jimmy Choo. She wore her hair down and curled under, and the entire look was glamorous yet understated, everything we've come to expect and love from Kate.

Click through above to see more photos of Kate's visit to the women's prison today.