With U2 arriving in Dublin for their homecoming gig this weekend, The Clarence Hotel will be brimming with VIPs. That is to say, the hotel owned by Bono, The Edge and Harry Crosbie will be more brimming with VIPs than it is normally at weekends.

Jack Nicholson, Tina Turner and Naomi Campbell are among the international celebrities who have forked out £1,450 per night to lounge in the open-air hot tub which comes with the luxurious penthouse suite.

"We have a reputation for discretion here," says the hotel's well-groomed general manager, Claire O'Reilly. "We can have people here that nobody even knows are in Dublin. . . If the press picks up on somebody being here we don't mind talking about it but we would never disclose who has been here."

Just 15 months since it opened its tastefully refurbished doors, the 50-room hotel has achieved world-wide recognition for its understated elegance and friendly and efficient staff.

It has been described as one of the 10 "hippest designer hotels in the world" (Tatler Cunard Travel Guide 1997) and one of the 25 "coolest places to stay in the world" (Conde Nast Traveller, April 1997).

Last Tuesday, with days to go before the VIP influx, Claire didn't know who exactly would be staying in the eight rooms which had been pre-booked by U2's management.

"We won't know until the last minute. We have to be ready to respond at the last minute and think about the logistics of it all," she says.

I spent Tuesday with Claire as she went about her duties in preparation for the weekend in which the hotel will be as much under the spotlight as U2.

9.30 a.m. Six managers who are responsible for 100 full and part-time staff gather in Claire's minimalist first-floor office. All the staff are addressed by their first names. The assistant front-of-house manager, J.P., says the previous night was hassle free. He checks the bookings list and announces: "16 in and 14 out. At the moment it's 76 per cent full. I hope we'll get 82 per cent tonight."

He reads down the list of guests, about half of them are repeat corporate clients who, if space permits, get automatic upgrades from superior (£165 per night) rooms to deluxe (£190 per night).

9.50 a.m. The staff depart and Claire talks earnestly about the hotel's vision and philosophy, gesticulating constantly with her lean hands.

"For me the experience has to be complete for all the guests. Wherever they go in the hotel, the service that they are experiencing has to be at the same level. Two things as far as I'm concerned make a good operation: one, everybody involved has to be passionate about what they are doing. You've got to have vision and make that vision happen and, secondly, all the time you have to demand from whatever you are doing nothing but the best."

Galway-born Claire (36), who worked for more than 14 years in four and five star hotels in London, clearly has both vision and passion in abundance.

10.30 a.m. Claire heads off with mobile phone in hand for an inspection of the hotel's rooms, toilets, corridors and facades. At the fifth-floor penthouse suite, she has arranged to meet Ariane, the accommodation manager who is in charge of overall presentation of the rooms.

Claire notices that the television remote control in one of the bedrooms has been changed because the previous one disappeared. The new one is a moulded curved shape rather than rectangular.

"Everything has straight lines here so things like this upset us," she says, holding up the oddly shaped object with disdain.

In the upstairs lounge, featuring white American oak, leather and stone, the designer stainless steel wine bucket has a dent in its rim. "God knows how the guest managed to do that," says Claire.

I comment that there are no U2 discs in the CD selection. Claire is prepared for this all-too-obvious observation. "That's deliberate. We never do the obvious here," she remarks.

In the residents' study, the hotel's flower arranger is tweaking a large display of white phalaenopsis. He is planning a themed arrangement for The Tea Room to coincide with this weekend's U2 concerts.

11.30 a.m. Claire links up with David, the maintenance manager who is overseeing the painting of the original window frames at the front. They enter The Tea Room and David tells Claire that the Japanese blinds which were removed the previous morning to be mended will not be back until mid-afternoon.

"They should have been back for lunch today," says Claire waving a cross finger. "That doesn't please me."

Noon: The hotel's public relations officer, Anna Coleman, arrives for a weekly meeting with Claire. They talk about inquiries for reviews and interviews from media outlets in London, Sydney, New York and Japan. They flick through press cuttings in which the hotel is mentioned. One is a reference to Naomi Campbell "snubbing" a fashion designer who was seated near her in The Tea Room recently.

1 p.m. Lunch is underway in The Tea Room. Chef Michael Martin says he expects it to be quiet, with only about 40 covers, as the courts are not sitting. His young and mostly male staff buzz around behind him; stirring, pouring, sauteeing, grilling and carefully arranging his creations in delicate little towers on the large white plates.

He stands calmly at the main counter, putting final touches on outgoing dishes and taking new orders.

3 p.m. Claire finally gets the chance to eat lunch in The Tea Room. "Some days are so frantic that you suddenly realise it's 5 o'clock and you haven't had lunch."

4 p.m. Claire leaves the restaurant and finds the foyer is in darkness. An electrician is fixing the lights at the reception and has turned them off for a few minutes. "I nearly freaked out when I saw that," she says.

Claire returns to her office to deal with some paperwork. J.P. pops his head in and they discuss the best way to notify guests that the lift is going to be out of action from 6 a.m. to 8 a.m. the next day due to painting work. They agree to put notes in all the rooms.

Claire dictates two replies to guests who had written effusive thank-you letters. "We do get complaint letters too," says Claire. "But it's rare and typically it would be from someone who ate in the Tea Room and didn't appreciate that fish is cooked just so or that vegetables are supposed be crunchy."

5 p.m. J.P. arrives to go over the bookings and staff arrangements for the next few days.

The weekend is still, says Claire, "in the hands of the gods". She checks that there are enough night-time staff rostered for the weekend. "I suppose we put pressure on ourselves to make sure it's extra good because they (U2) are our owners after all."

5.30 p.m. The assistant general manager, Olivier and says that a leak in the dishwasher earlier in the afternoon has been fixed and the kitchen is back in operation. The Japanese blinds have been returned to The Tea Room.

Claire says she wants to draw up an action plan following on from a brain-storming session last week to keep staff focused for the next six months.

7 p.m. Claire and Olivier take a final tour of the building before going home. Claire says it has been a fairly normal day. "You have to just take the opportunity when you get it to go early before something happens and you're here all night."