Prince William and Kate celebrate their alma mater at London gala

Prince William and his wife stepped out on Thursday to celebrate the 600th anniversary of their alma mater, St. Andrews University.

The Duke and Duchess of Cambridge, both 30, attended a fundraising dinner for the Scottish school at Middle Temple Hall in London.

Kate, 30, donned a black lace gown by Alice Temperley for the event. She originally wore the dress to the London premiere of "War Horse" last spring.

At the gala dinner, William spoke of "happy, happy memories" from his time at the school, the Daily Mail reports.

"We love it for its traditions - traditions that lie at the very heart of Scotland's history," he said in a speech, according to the BBC. "We love it because it made us look beyond St Andrews, beyond the borders of Scotland, to the wide world."

"But perhaps most important of all, we love it for the friendships it has given us," he added. "As I look around this hall tonight -- and even take a peek at the person sitting three from my left [Kate] - I thank God for those friendships -- our friendship -- forged in our ancient halls."

William and Kate met in 2001, while attending St. Andrews. They both graduated in 2005 -- him with a degree in geography, and her in history of art. It's said that Kate caught the prince's eye while modeling a see-through dress at a university fashion show, which she reportedly joked about while speaking with a current student at the fundraiser.

According to the Daily Mail, Kate was heard telling the female student, "I hope you weren't involved in the fashion show, you never know what you are going to be asked to wear!"