William and Kate at gala for St Andrews University

The Duchess, who is four months pregnant, arrives with Prince William for the dinner. Picture: AP

In a speech to guests – who had paid up to £6,400 a head to attend the dinner at the Metropolitan Museum marking the 600th anniversary of their alma mater – Prince William said: “I don’t need to tell all of you just how much St Andrews University means to me and Catherine.

“It goes without saying to those in this room that the education we received there was first class.”

He then joked: “It’s often said by the undergraduates that you leave the university in one of two states: either married or an alcoholic. Fortunately for Catherine and me, we ended up married.

“But for those of you who are parents of undergraduates right now, I give you one tip: ask your son or daughter over the holidays if they know what Ma Bells is. If they answer yes, perhaps remove their wine glasses out of reach.”

Ma Bells is a pub frequented by many St Andrews students – including William and Kate during their time in the town.

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Yesterday, the university revealed that the event in New York had raised £2.2 million towards student scholarships for those who would otherwise be unable to take up the offer of a place.

The university, which is aiming to raise £100m from international fundraising, has so far reached £52m. A total of £13m is to be used for scholarships.

Kate, who is four months’ pregnant, wore a midnight blue gown by British designer Jenny Packham and a pair of diamond and emerald earrings to Tuesday night’s dinner.

The royal couple had been greeted on the museum’s steps by a guard of honour of fellow St Andrews alumni wearing the university’s traditional red gowns. A piper played Scotland the Brave as they headed into dinner.

The black-tie event featured a guest appearance by US comedian and chat show host Seth Meyers, who gave the toast. He was drafted in to replace Tom Hanks, who had to pull out for personal reasons.

Opera singer Renée Fleming sang Have Yourself A Merry Little Christmas and the Puccini aria O Mio Babbino Caro.

Other guests included Princess Eugenie, US Vogue editor Anna Wintour and Mary-Kate Olsen, the actress turned fashion designer who is one half of the Olsen twins, and her partner Olivier Sarkozy – half-brother of the former French president.

In his speech, the duke, who is patron of the 600th anniversary fundraising campaign, spoke warmly of the university from which he and his wife graduated in 2005, saying: “St Andrews’ blend of academic excellence, mixed with a liberal approach to critical thought and creative reasoning, is one that both our nations, on both sides of the Atlantic, credit with importance.

“In particular, St Andrews exists at the pinnacle of a noble Scottish tradition of intellectual freedom and the nurturing – in fact, I would say, flourishing – of arts and science. “It feels like a place where no truth goes unquestioned and where there is much more discovering to be done in the world.”

In the programme, he added the personal note: “For Catherine and me, it will always be a very special place and we have the warmest of memories of our time as undergraduates and the friends we made there.”

After the gala dinner, the couple boarded a plane home to be reunited with their son, Prince George. They took with them the gift of a miniature red gown presented to them for their son by Professor Louise Brown, the university’s principal and vice-chancellor.

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