Behind the baize door at the Dorchester

The revered hotel reveals all to 20 lucky people on an exclusive tour later this month as part of the London Open House weekend. But you don't have to win the ballot because Adrian Mourby has had a sneak preview

There is probably no hotel that sums up British luxury better than The Dorchester. The Ritz has glitz but it's a French import. Claridges sometimes seems a holiday home for dispossessed European royalty.

The Dorchester, however, is quirky, eclectic and very British. Having passed by many times, but only ever gone in for tea, I know exactly how the ballot winners will be feeling on 14 September. That is when the names of all those applying to join the hotel's Open House tour, a fortnight from today, will be placed in the doorman's hat and 20 names will be pulled out.

The Dorchester sits like a section of some 1930s luxury liner plonked down on Park Lane: no two bedrooms are the same; Highland warriors, clad in tartan, are stencilled on to the walls of The Grill; the Orchid Room was decorated by one of the Queen Mother's designers to look like a giant piece of blue Wedgwood.

Despite it's old-world appeal to foreign tourists, almost half the hotel's custom is from the UK. They arrive by Tube or pull up in mud-spattered Range Rovers. Prince Philip spent the night here before his wedding to the then Princess Elizabeth in 1947. You can't get more British than that.

I arrive early for my preview of the behind-the-scenes tour. Not only will the Open London weekend winners get access to some of the best suites, they'll also see a slice of the hotel's life beyond the green baize door. My host is Rosanna Crawley, who arranged The Dorchester's involvement in London's big open day.

Together we poke our heads into the laundry room where guests' shirts are washed, pressed, then boxed in cardboard and cellophane so slickly that you could set up a stall and sell them. We also chat to three of the hotel's flower ladies, Wendy, Mandy and Izumi, all handmaidens to the head florist, Belinda Bowles. They seem very happy in their small workshop on the second floor but then, if you like flowers, there's a lot of job satisfaction to be had at The Dorchester. Even on a quiet day they process about £1,500 worth of blooms, rising to £30,000 for big functions.

In the kitchens – the biggest in Europe – we miss Claude Lamarche, the pastry chef who isn't in until later, but I do get to see the special, extra-long Dorchester loaves arriving ready-sliced. It is from these that Bernie, the Sandwich King, creates more than 2,000 rounds a day.

As we emerge, our way is briefly barred by the powerful figure of Henry Brosi, the Dorchester's executive chef from Heilbronn-Sontheim in Germany. At the moment he oversees more than 100 colleagues producing food in six different kitchens. Henry tells me that on 20 September he will be demonstrating his new project, the refurbished Krug Room, an exclusive dining chamber that seats 12 and is situated inside the kitchens behind electrochromic glass which, at the touch of a button, Henry can make opaque, for privacy, or clear again when he thinks you will want to watch the food being prepared. Dishes in this room will be designed to complement the hotel's collection of wines and Krug Champagne. "We can arrange pretty much every vintage," Rosanna tells me.

Of course they can.

Now it's time to see the public areas. I can tell that my host is enjoying this as much as I am. Rosanna is young but she feels, in her line of work, there's nowhere to go after The Dorchester. "Nothing's going to better this," she tells me as we take a lift up to the eighth floor. Together we slip through an unremarkable panelled door and up a flight of steep, carpeted stairs to the Harlequin Suite, revamped by top New York designer Alexandra Champalimaud. This is the most expensive of the three suites added in the 1960s. Elizabeth Taylor always stayed here and the hotel installed a pink marble bathroom just for her. It's been preserved exactly as it was on the day that she signed Hollywood's first $1m contract, given for her role in Cleopatra. Actually, it's more functional and less well finished than you'd expect. We forget how close to post-war austerity the early Sixties were.

The Harlequin Suite costs a cool £7,450 per night, and that's without VAT. It's difficult to imagine the kind of income someone needs in order to blow that amount of money on one night in a hotel, although I know that the likes of Nicole Kidman and Arnold Schwarzenegger may well have done so. No expense has been spared on the decor – American walnut floors, gold curtains from Thailand, walls upholstered in ivory silk – but I can't help feeling that for that amount of money I'd want Arnie and Nicole to be sharing it with me, and for them to tell me afterwards that I was their best friend ever.

As Rosanna opens the door to the suite's kitchen, we come face to face with Miguel Rodriguez-Silva, one of three butlers assigned to these suites under the guidance of Paul Pritchard, head butler and late of the Royal Household. Miguel is all smiles as if he is delighted rather than surprised to see us. He has just prepared coffee for the new arrivals who will be up shortly, but there's absolutely no sense of rush. He is happy for us to wander out on to the terrace, which has a superb view of Hyde Park. Apparently Alfred Hitchcock, looking at this view, declared The Dorchester a perfect place for a murder because there was so much space opposite for burying the body.

Rosanna points out the terrace of the Audley Suite next door where a white marquee has been pitched. Evidently the star who is staying there (I know she'll never disclose his name) wished to watch TV out of doors but found the glare on the screen too bright. I think most hotels would suggest that Sir might find it easier to watch TV back in his room, but not The Dorchester. This is the hotel that recently let a well-known American singer redesign his suite so it resembled a cabaret where he could entertain friends every night after the curtain came down on his West End show.

On our way down we call in at The Penthouse and Pavilion, a suite of rooms by Oliver Messel, Britain's most celebrated theatrical designer in the 1950s. The suite has its own terrace with a Rococo fountain, and is very popular for weddings. The rooms take Messel's own sets for The Magic Flute and Sleeping Beauty as their inspiration; glass-panelled walls are overgrown with plaster vines. It's extremely theatrical and rather overwhelming. More to my own taste is the Messel Suite on the seventh floor for which the brief was simply a set of rooms that Messel himself would like to live in. He wasn't the only one. Noel Coward and Marlene Dietrich always stipulated this suite whenever they stayed and, in recent years, that grand old thespian Sylvester Stallone has followed suit. The lavatory seat is shaped like a giant scallop shell, covered in gold leaf. It's difficult not to imagine Sly's muscular bottom framed by that.

Rosanna has more in store as we return downstairs. The Byford Room is a remarkable oak-panelled salon that pre-dates the hotel's construction by more than a century. The Dorchester was created by the McAlpine and Gordon families in 1931 and was developed on top of and around Dorchester House, one of the early 19th-century palatial homes that lined Hyde Park. Rather than demolish the entire building, the architects built around several rooms. This is the only one remaining. Stepping inside is an extraordinary moment, like a time- travel fantasy, as I cross the threshold and two centuries.

Rosanna is keen to show me the latest additions to the hotel. Off the Promenade, the long corridor strewn with sofas, aspidistras and pianos that runs the length of the hotel, lies the new two-Michelin star Alain Ducasse restaurant. Its oval private dining area is curtained off by thousands of strands of illuminated white beads; flowers are banned from all the tables at Ducasse's request.

Beyond that, the duplex Crystal Suite is still being refurbished in time for 20 September. All I can see today is a glittering piano covered in mirrored mosaic tiles, one of two that used to belong to Liberace. "I bet you can guess who owns the other one," Rosanna prompts. And I'm right. It's Sir Elton. Martin Hulbert, the designer of the new Crystal Suite is on site today and we discuss the staircase that winds up from the piano to the first floor. "Wonderful for making an entrance," says Martin and, again, we're all thinking Elton.

The last stop on my tour is below ground level. The new Dorchester spa is also Martin's work. Its style is cool, with clean lines and polished chrome doors. Again, it reminds me of a 1930s liner. "That's very much been the inspiration," Martin agrees, "though we've not been slavish. We wanted to avoid something that looked like a sequence of treatment rooms."

Finally it's time for lunch, which I'm offered in the spa's intimate six-table restaurant. "We call it a spatisserie," says Rosanna. "As far as we know, this is the first spatisserie in the world." I wouldn't be surprised. Just about everything at The Dorchester is different. So why shouldn't this unique hotel add a new word to the Oxford English Dictionary?

Compact facts

How to join

To enter the draw to see behind the scenes at The Dorchester – the first time the hotel has opened its doors in such a way – email your name to diary@thedorchester.com. Twenty winners will be picked from a ballot and notified via email. If you don't make it on to the 20 September tour, you can still see some of the hotel over lunch or dinner in The Grill where the new head chef, Brian Hughson, has introduced a two-course lunch and pre-theatre dinner menu for £21. Or sign up for the Krug Room masterclass programme with the executive chef, Henry Brosi, starting on 17 October at £150 per person.

Further information

The Dorchester, Park Lane, Mayfair, London, W1K 1QA (020-7629 8888; thedorchester.com)