Every weekday, you will find her in her own chair next to the coffee maker. "It's very old. It survived a fire in October 1972. The boys went skiing with the insurance payout," recalls Rie Schild, the housekeeper of the Minerva student house 't Heerenhoeckje on Rapenburg 110. A photograph of the burning house is stuck on the wall among dozens of other snaps and newspapers cuttings of her with the residents – more than a hundred – she has seen come and go. Last Saturday, they all got together to celebrate her ninetieth birthday. "The father of one of the residents, a former resident, picked me up from my house in Oegstgeest in his Ferrari. For a moment, we went really fast – I could feel the car pull under me. Such fun."

Even now, she makes the coffee and does the dishes. "And provide some companionship and a bit of discipline." The sjaars (first-years) of the house make sure the beer is cold and the rubbish bins are emptied. "Or else I tip them out in their rooms," explains Schild. And she still wears an apron. "I used to buy them myself, but the boys didn't like them. Now I get them as presents, usually when that book is published. What's that book called again?" she asks resident Yoram Kannangara (21, a fourth-year Anthropology student) who is sitting next to her and nearly asleep in his much more comfortable chair. "The Almanac," he mumbles. Schild continues: "Oh, that's it. And sometimes they bring one back from their holidays. This one's from France. Nice, isn't it?"

She looks remarkably lively for a ninety-year old, especially when she is surrounded by residents with sleepy eyes, arriving one by one in their dressing-gowns. Most of them have hardly slept after leaving the Minerva party in honour of the American election night. In fact, Kannangara is on his way to bed.

Schild grins. "I met him in the alley shortly before half past nine."

"I attended Prince Willem-Alexander's graduation party. He used to come round here a lot." The ten residents had put eleven names down, but Schild was turned away at the door. "I wasn't a 'man' you see, but I shook the Prince's hand and said that I actually thought he was a prick. He spluttered that he couldn't help it - everything had been arranged for him. He had no say in it."

Many of the fathers of new residents are themselves former residents. Schild adds: "Those were the good old days. They could stick around until they were about 26." The mothers are particularly happy that she is there. "They don't recognise their own sons after a year, because they are more affectionate, nicer and don't talk back anymore because I smack them if they do. I haven't had to smack this one yet," she says, pointing at the house sjaars, Willem Bijleveld (18, International Studies), who, in his dressing-gown, has just joined us. "But I'm not cheeky," he observes bashfully. "He's just a babe," explains Schild with a note of pity.

Except for the new murals for each of Rie's anniversaries, the house has scarcely changed over the years. "They frequently bring stuff along. If someone's granny dies, we get new cups." She thinks that the students are sweeter-natured nowadays. "Sometimes they'll say, 'Oh, stay a bit longer and we'll fetch some croissants.' So then I'll stay here for a bit. I've had time on my hands anyway since my husband, Frans, died some years ago. He would never have approved."

Nevertheless, in 1984, she went on a two-week holiday with two of the residents. "I said that I would join them for a joke, but they took it seriously. Frans wouldn't believe me and when I didn't come home, he kept asking where I was. I was on my way to Spain."

She has spent more time travelling since his death. "Then they have to make their own coffee. Mind you, most men can even cook nowadays, so that helps. I prefer a man who can't even boil an egg, then he won't notice if the meal's messed up."

She was awarded an honorary medal by the Queen in 1992. "Willem-Alexander had nothing to do with it, because he has no say in anything anyway. A resident had arranged it secretly. And I had been cross with him because, for a short time, he missed so many coffee breaks. If you miss the coffee break, I'll pour ammonia on you. Hangover or not," she says fiercely.

The bottle of ammonia is ready next to her chair. The same fate awaits any unknown girls she might encounter of a morning.

"Well, they shouldn't behave so outrageously. I'll make allowances for a steady girlfriend from Amsterdam, because you can't turn a girl out onto the streets at night. But no other ladies are allowed in here before ten o'clock. It would give the house a bad reputation."