Diary of a nervous star

London

I might as well start by dropping a name. Once, as we began shooting a big budget movie called The Postman, Kevin Costner asked me, "What's it like to have your dream come true?" I rather arrogantly and ungratefully explained to him that to come to Hollywood and make a movie wasn't my dream; that would be to play the Great Classical Theatre Roles. Ten years have intervened between the question and now; extraordinary times from Maui to Madagascar, from pretending to be a mother to 14 children to having a real one of my own.

For the first time in two years, there is no nappy-change kit in my bag, no box of raisins. No, I am cycling to rehearsals with The Changeling in my backpack and Beatrice Joanna's lines highlighted in yellow. For the first time since I went into labour I am afraid, but now I deal with fear via the responsibilities of motherhood - rehearsals aren't scary, they're ex-cit-ing, and we like meeting people, don't we? Say: "Hello Everybody! My name is Beatrice Joanna, and I like to have adulterous sex with my deformed servant."

Sceaux

To be in Paris makes everything, even the technical rehearsal, a bit glam. A glass of wine at lunchtime with your steak frites, unthinkable in Southwark, is suddenly de rigueur. I am speaking French, talking about theatre and work and the text in French, free to shrug and gesticulate and be passionate. I get very distracted by the French surtitles provided by the irrepressible Harold. How the hell is he going to translate: "where swine deformity swills the tears of perjury that lie there like wash"?

We keep working on the play until we are standing waiting to go on stage, and the first night becomes a continuation of our six weeks of intense rehearsal. I come round halfway through the curtain call, realise I have been slapped and shagged, and shown my bottom in front of a theatre-full of strangers and beam like an idiot. A strong rhythmic clapping begins, which we are assured, is a sign of appreciation rather than fanatical impatience as it is in England. We get through our repertoire of bows and have to choreograph more for the next night.

Juliette Binoche and Peter Brook come to the show, each bringing a particular brand of fear. The boys cluster round Binoche. The gaffers (the director Declan Donnellan and the designer Nick Ormerod) are beaming because Brook evidently approves and is enthusing about how modern, how clear, thay had made this dark Jacobean play. N and D leave for Bogota and our days are free, but I have become addicted to rehearsal and don't feel ready to cope without them.

Attempts to economise and live within the theatrical per diems include making a sandwich for lunch out of the buffet breakfast, and washing knickers in the basin. Gone are the days of lavish on-set catering and the Four Seasons Hotel delivering my M&S smalls wrapped in tissue paper and sealed with a gold sticker.

Reims

Champagne is running in the streets and the cafés and we sit in the spring sunshine in the Café du Palais, where a model of a cloven-hoofed, horned woman shares our table. I name her Beatrice Joanna. I start ordering kir royale it as if it were lemonade. I wake at 6pm and find my face has been have been rearranged by Arcimboldo.

We wander around the cathedral in a kaleidoscope of stained glass, illumined by the afternoon sunshine. My fellow actor Jim Hooper spots Jodie McNee (another cast member) welcoming us in through the east door, except Jodie has a nose and the smiling angel of Reims doesn't.

Nancy

The centre of the city is beautiful and its residents clearly highly cultured, but it is pouring with rain and I have too much time in the high-rise hotel to think about home.

The way I miss my daughter Esmé is to worry about her. It is not a pleasurable longing. It contorts my body and scrambles my brain, makes me stop breathing, clench my jaw and my fists, it makes me frown, and makes me blind and deaf, in fact entirely without sensory perception. I can sit indefinitely, unaffected by time or commitments and just worry until my head hurts, then snap out of it, look at a clock and 45 minutes have disappeared, unaccounted for, in a labyrinth of calculations - if I had gone home for the rest day in Reims, seven hours travel each way, she would have been asleep when I arrived, so, seven waking hours with her for 14 hours travel, I should have done it, why didn't I go?...

Nick and Declan return, watch the show, and summon Tom (Hiddleston, my co-star) and me for a three-hour rehearsal the next day. I cancel a plan to go to the Musée des Beaux-Arts and lunch at the Excelsior.

I brace myself. I have heard about this. Just when you settle into a performance, have found your route through the text, know where you can get a laugh, where you can relax and let the others take the strain, Declan comes back and takes away the things that make you so sure of yourself. I remind myself that this is why I wanted to work with him, that to be complacent, to churn out the same version of the same performance every night is exactly what I wanted to avoid. But I cling to my favourite moments like they are my diamonds, finding excellent reasons why they should remain in my bony clutches: this reading of the text is anti-feminist... it marginalises the character... I can't do blushing virgin at my age...

But he is right. The work we have done causes a chain reaction from all the actors, and the play is revitalised, reinterpreted, and everyone is on their mettle. A full and sustained standing ovation determines that we love Nancy despite the evil acoustic and hollow stage.

Luxembourg

However irreverent and unimpressed by wealth or power actors pretend to be, they love an ambassadorial do, and our hosts for the first night party are the British ambassador to Luxembourg and his partner, Tony. We get hopelessly lost on the way from the theatre and spend an hour outside the wrong building drinking beers with an angry post-show thirst and getting lairy. Will Keen (another cast member) points out that there is no point in phoning for directions, as diplomacy would dictate that the ambassador should meet us halfway, so we may as well stay where we are.

Eventually we find the Union Flag fluttering over a grand town-house and the ambassador and Tony greet us warmly at the bottom of a sweeping staircase. There is abundant champagne left despite the best efforts of the gaffers to finish it before we arrived and ,at about one in the morning, we all move out to the gazebo to admire a view of the gorge.

I was curious as to how a diplomat would get rid of a large crowd of drunk actors who had settled in for a long night's boozing courtesy of the taxpayer, so when he popped his head round the gazebo and said he was off to bed and what a pleasure it had been to meet each and every one of us equally, I asked him if that was a diplomatic way of indicating that he'd like us to go. With admirable diplomacy, he said: "Well, soon, but don't rush".

Frankfurt

We are part of the Frankfurt Festival of European Theatre and delighted to be called a "splatter-thriller."

We decide to and go to see the Catalan company performing an obscure Brecht. It is bizarre and unpredictable, featuring a child breakdancing with a heavily pregnant woman, a video of sharks tearing at each other's flesh, men in suits gesticulating in a perspex box, live electric guitar crashing out rock chords, and a papier mâché cow. The text is whispered through hand-held mikes, in Catalan (which I don't understand), surtitled in German (which I don't understand). I am not sure what I have seen, but I applaud and cheer and meet the performers afterwards at a drinks do, but they are glued to the Barcelona-Milan football game.

The bonhomie created by a Barcelona victory and a couple of glasses of Riesling makes me feel part of the warm, creative family that is the European Theatre. Buenas noces! Bonne nuit! Guten nacht! Tomorrow night the festival programme promises an Italian troupe which practises "the art of Sicilian Cunto, an ancient and fascinating form of oral storytelling." Yes, please. Buona notte.

I prepare myself for a reunion with Esmé that fails to follow the Hollywood template. I assume that she will cling to Rhashan, my husband, who is there when she sleeps and there when she wakes and catches her when she falls. She has every right to regard this stranger with suspicion. But, as I approach my family at the train arrivals, my bags fall to the floor, she throws her head back, runs fearlessly into my arms and whispers, "All the family together again, Mummy and Daddy and Esmé." So this is what it is like to have your dream come true?

I am aware that to say that you have exceeded your expectations of absolute happiness looks like showing off. But not to say it is ungrateful. I didn't expect it to happen. But this... this is perfect.

© Olivia Williams 2006

Olivia Williams is in 'The Changeling' at Warwick Arts Centre, Coventry ( www.warwickartscentre.co.uk; 024 7652 4524) to Saturday and at the Barbican, London EC2 (0845 120 7515; www.barbican.org.uk) from 11 May to 10 June