But almost immediately she frowned. For if Maxi did not get hold of Putzerl, the pearls would have to go.

‘I always stab the air with my left hand,’ said Pino Mastrini, greatly offended at being asked to extend his acting range. ‘Always. I stab — so — and then I drop down on my left knee, so. Always.’

‘That’s exactly what I’m complaining about,’ said Jacob, wiping the perspiration from his forehead.

‘In zis bodice I cannot zink! I cannot zink even ’igh C, and ’igh F you can forget absolutely it,’ complained Raisa, erupting from the wings, followed by an infuriated Frau Pollack with her mouth full of pins.

‘The starcloth will have to be cut down, Herr Witzler. It’s half a metre too long.’

The International Opera Company was preparing for its mysterious assignment in June. Jacob had kept Farne’s secret, and no one knew who their patron was or whither they were bound. But underlying the speculation and the rumours was a growing sense of excitement, as though this was the chance that they had all been waiting for.

And so they worked. The Magic Flute had been in the repertory for years, but now they prepared to study Mozart’s immortal singspiel as though it had at that moment just been composed.

Jacob himself was in a white heat of expectation. He had seen pictures of Pfaffenstein rearing romantically on its crag above the lake, heard descriptions of the enchanting theatre. Now he dreamed of the Perfect Performance in the Perfect Setting in the presence of the Perfect Patron who would lead the company from financial darkness into light. In the cafés, among his acquaintances, Jacob showed off and swaggered; he ran up new bills and defaulted on his creditors, but over his opera he dreamed true. And because of this, though they might complain and argue, nobody failed him.

‘Where’s Bubi?’ cried the Rhinemaiden, who had come along to help.

‘I have him, Frau Witzler.’

Tessa appeared briefly in the pit carrying the Witz-ler’s three-year-old son on one arm and a plate piled high with sandwiches in the other. She emerged in the rehearsal room where Klasky — cursing the violins in Hungarian, the cellos in Czech and the woodwind in Serbo-Croat — appeared to be preparing Mozart’s score for an audience of ranking cherubim.

‘Thank you. Put them over there,’ said Klasky, glaring at the orchestra who, having rehearsed for five hours without a break, now foolishly assumed that they could eat. He passed a moist hand absently over Bubi’s blond curls and smiled at Tessa. She was a nice little thing, always willing to help. Perfect pitch, too… Pity there was never any time. Still, perhaps it was just as well. Like Chopin, who believed that to approach George Sands in love was to deprive the world of an étude, Klasky was convinced that women drained away a man’s creativity and it would never do to dissipate his energy. For in spite of the recent spate of rehearsals, Klasky had made a real breakthrough with his own opera. By changing the wronged husband from a policeman to a railway porter, he had unblocked his imagination in a most amazing way. A chorus for platelayers and signalmen had come to him in a single flash of inspiration; a soliloquy for an engine-greaser, a kind of Holy Fool who would speak for the oppressed proletariat, virtually wrote itself.

And sighing, for the girl was charming, he picked up his baton once again. ‘From the letter D, gentlemen. And remember that sostenuto means sostenuto. Even for Herr Katzenbirger it means sostenuto.’

As the time drew nearer for their departure, the company’s preparations grew more frantic.

‘I am not a canary,’ announced Raisa, arriving for a morning rehearsal. ‘I cannot zink at ten o’clock,’ but she sang. The coloratura Jacob had filched from Dresden to play the Queen of the Night fell off her stepladder, twisted an ankle, and climbed up again to sing ‘O Zittere Nicht’ in a way that had the orchestra banging on their music stands. Boris stayed up until 3 a.m. creating exotic head-dresses for Sarastro’s priest. Even Frau Pollack, presented with new fabrics after years of making do, forgot her almost-eaten great-uncle and trod the treadle of her sewing-machine like a Valkyrie.

As for Tessa, she was everywhere: prompting, copying, sewing, ironing and only once, very quietly and unnoticed, fainting in the laundry room when she had missed a little more food, a little more sleep than her small frame could endure.

On a Saturday evening, just five days before they were due to leave, Jacob received a phone call in his office which sent him hurrying in search of his under wardrobe mistress.

‘I’ve just had a call from Herr Klasky, Tessa. He’s conducting at the Musiksverein at eight-thirty and he’s forgotten The Button!’

‘Oh no!’ Tessa’s eyes were wide with concern. ‘Is it a première?’

Jacob nodded. ‘Berg’s Concerto. We must get it to him. It would be a disaster if he got upset now, so soon before the tour.’

All performing artists are superstitious and Klasky, though technically sane, could only conduct a première while in possession of a small, mottled object suggesting, with its faint air of decay and transparency, the shed milk tooth of an undernourished child, but authenticated without a doubt as the waistcoat button of Ludwig van Beethoven himself.

‘He’s rung his housekeeper,’ Jacob continued. ‘He wants you to run round quickly and fetch it and leave it at Sachers at the reception desk. He’s dining there now on his way to the hall. Can you manage that?’

A faint shadow had crossed Tessa’s face at the mention of Austria’s most famous hotel, once the favourite haunt of the aristocracy, which the terrifying Frau Sacher still ran with a complete disregard for recent changes. But she only said, ‘Yes, Herr Witzler,’ and was presently found by the Littlest Heidi, rummaging hastily in a wicker skip for something to replace her paint-encrusted smock.

Heidi Schlumberger was not only the smallest but the prettiest and sweetest of the Three Heidis, her blue eyes permanently widened in admiration of the world.

‘I’ve got a Sylphides dress that’s spotless,’ she said now, taking Tessa by the hand. ‘Come along, I’ll show you.’

‘Is it suitable, do you think?’ said Tessa, when she had slipped it on and stood looking at herself, white, gauzy and rose-embroidered in the mirror of the chorus dressing-room.

But what was suitable for the delivery of Beethoven’s waistcoat button to Sachers? — and anyway, there was no more time. Thanking Heidi profusely, Tessa ran out into the street.

Guy had spent the day before Nerine’s arrival in a kind of Odyssey, revisiting the places where he had been with her. The old hunting pavilion in the Prater where he had picked her a bunch of early scillas like little sapphire stars… the chesnut tree by the gates of the Academy where he had watched for her light at dawn… the room in the Kunsthistorisches Museum with its famed and fabulous Breughels in which Nerine — hiding from the other girls — had stood beside him to gaze enraptured at the master’s complete and all-embracing world.

Now, strolling back through the Inner City past scalloped fountains, equestrian statues and the quiet facades of palaces warm in the golden light of evening, he could almost believe that the city, like himself, was waiting for his love.

He crossed the Albertina Platz, exchanged bows with the Minister of Trade who was assisting his portly wife into a fiacre, turned down the Philharmonikerstrasse and entered his hotel.

The foyer was almost deserted, for they had begun to serve the evening meal. But at the far side, between two Venetian mirrors, he glimpsed a small figure in white backed against the red-damask covered wall. A figure imprisoned by the fat, spread-eagled arms of a bald gentleman in evening clothes, his back to Guy, who was bending over her.

Guy approached and as he did so, the anguished face of Witzler’s under wardrobe mistress appeared briefly from behind the bulk of her captor, lit up in recognition of Guy and vanished once again.

A certain melancholy settled on Guy. The man endeavouring to pin her to the wall was old, unsteady on his feet and probably quite genuinely under a misapprehension for the glimpse of Tessa, her throat and bare shoulders rising from a cloud of white, hardly suggested a respectable Viennese hausfrau waiting for her spouse. Which was a pity — for Guy, penned for weeks in the Treasury, was in the mood to do justice to a prolonged, well-matched and bloody fight.

Now he merely seized the man by the shoulder, spun him round and in tones as polite as they were menacing, said, ‘This lady is with me.’

Rubbing his shoulder and muttering angrily, the old gentleman tottered away. Guy, left looking down at Tessa’s fragile, serious little face, transcending the absurd romanticism of the costume, was more than ever inclined to exonerate her tormentor.

‘How old are you?’ he asked abruptly.

‘Twenty. Well, almost.’

Guy, who had been toying with the ‘I am old enough to be your father’ approach, abandoned it. At eleven he had not really been prepared for parenthood.

‘You shouldn’t be here alone,’ he said, his voice still harsh. ‘It’s most unsuitable, you must know that.’

‘Yes… I’m sorry.’ Only the ghost of a sniff, a finger pressed against the corner of one eye as if to hold back an impending tear, betrayed her recent strain. ‘I had to deliver something for Herr Witzler.’

Guy’s thick brows drew together in a frown. What did Witzler mean by exposing her to this? Was the child never supposed to eat or sleep?

‘You had better stay and have some supper. My secretary’s probably waiting in the dining-room. She’s a formidable lady, but she’s got a heart of gold. Come and join us.’