The rout of Sultan Mahomet’s troops after the second siege of Vienna, which banished the Turks for ever from Christendom, set in train a riot of new building as cannon bastions and barrier walls were blown up and the years of imperial splendour under the ever mightier Habsburgs were reflected in Pfaffenstein’s steadily increasing grandeur, opulence and pomp. Ignoring, but never quite managing to erase, the dungeons built deep into the rock, the torture chambers and oubliettes of the earlier fortress, the princes of Pfaffenstein built a palace along the southern front, the windows of its great state rooms sheer with the crag as it rose above the lake; blasted terraces out of the rock and threw pepper-pot turrets on to the flanking towers. A musical Pfaffenstein built a theatre, an Italianate one arcaded the courtyards, a prince of the Church enlarged the Romanesque chapel to form a soaring, gilded paean to the glory of God.

Larger than Hochosterwitz, more heavily fortified than the Esterhazy palace at Eisenstadt and far, far older than the castles that the poor mad Swan King Ludwig had built to the north in Bavaria, Burg Pfaffenstein, by the end of the nineteenth century, had become the subject of innumerable paintings and the inspiration of countless minor poets. The redoubtable Baedecker, when he arrived, gave it three stars.

To this castle, driving himself in his custom-built, tulip-wood Hispano-Suiza, came Guy Farne on a spring afternoon in 1922, with a view to purchase.

He came, as all who come from Vienna must, by the road which skirted the western side of the lake and as the fantastic, towering pile reared up before him, his wide mouth curved into an appreciative smile.

‘Yes,’ he said to the young man sitting beside him, ‘it will do. Definitely, it will do. You’ve done well, David.’

His secretary, David Tremayne, whose fair good looks and puppyish desire to please concealed a tireless efficiency, turned a relieved face to his employer. ‘I thought you’d like it, sir. I saw a few others but I don’t know… This one put them all in the shade.’

‘It certainly makes its own quiet statement,’ said Guy sardonically.

But as he switched off the engine and got out of the car, he momentarily caught his breath. Burg Pfaffenstein’s role as fortress, as refuge and as palace was evident in every stone. Now, in the still, green lake which mirrored with exquisite accuracy each tower and pinnacle and glistening spire, Guy saw it in another guise: as Valhalla or Venusberg — the castle as dream.

‘You’re certain the owners want to sell?’

‘Absolutely, sir. There are only the two old ladies left now and a great-niece in Vienna.’ And David fell silent, thinking with compassion of the proud, impoverished families he had visited in his search, all desperate to offer him their ducal Schloss or moated Wasserburg or hunting lodge.

Guy nodded, measuring the road which passed under the crag at the head of the lake and then vanished into the ravine.

‘Let’s see if we can make it without oxygen, then,’ he said and climbed back into the car.

But as Guy drove skilfully round the hair-raising bends that led up to the Burg, David was frowning. His instructions had been simple: to find an impressive and imposing castle (‘toffee-nosed’ was the word his employer had used, reverting to his origins) which the owners were willing to rent or preferably to sell.

Only why? This was something Guy Farne had not chosen to reveal to his otherwise trusted secretary, and the whole enterprise seemed totally out of keeping with what David knew of his employer’s tastes and inclinations. A millionaire he might be, and several times over, but his personal habits were spartan to a degree which caused deep pain to Morgan his chauffeur, to Miss Thisbe Purse, his stenographer, and at times to David himself. Farne’s indifference to comfort, his ability to go without food or sleep, his detestation of pomp were a byword, nor had he troubled to conceal his contempt for those post-war profiteers who conned the newly-poor out of their houses and possessions. True, his sojourn in Austria was likely to be of some duration and he needed a base — but why this gigantic castle? In Brazil, where other men of his wealth had bought palaces, he had lived in a simple if lovely facienda by the river, his only extravagance a steam yacht with which he explored the mazed waterways of the Amazon. In London he lived in an apartment in the Albany, in Paris in a roof-top flat in the Ile St Louis which but for the glory of its plumbing might have belonged to any Left Bank painter or poet. Only on movement — elegant boats, fleet cars and (his latest acquisition) a small bi-plane — did Farne habitually spend the awe-inspiring sums which betrayed his stupendous wealth.

They had negotiated that last hairpin bend, crossed the drawbridge, been sneered at by the griffins on the gatehouse arch and now drew up in a vast and silent courtyard.

Ten minutes later, having followed an ancient retainer in the Pfaffenstein livery of crimson and bottle-green along an immense groin-vaulted corridor and through a series of shrouded and magnificent rooms, they found themselves in the presence of the two old ladies who were now the castle’s sole occupants.

Augustine-Maria, Duchess of Breganzer, was in her eighties, her eagle’s beak of a nose and fierce grey eyes dominating the wrinkled, parchment face. The Duchess wore a black lace dress to the hem of which there adhered a number of cobwebs and what appeared to be a piece of cheese. A cap of priceless and yellowing lace was set on her sparse hair and her rather dirty, arthritic hands rested on a magnificent ivory cane which had belonged to Marie Antoinette.

Her sister-in-law Mathilde, Margravine of Attendorf and Untersweg, was a little younger and in spite of recent shortages, resolutely round-faced and plump. Unlike the Duchess who had received them standing, the Margravine remained seated in order to embrace more efficiently the quivering, shivering form of a goggle-eyed and slightly malodorous pug whose lower extremities were wrapped in a gold-embroidered Medici cope.

Driven back room by room by their poverty, the demands of the war (which had turned Pfaffenstein into a military hospital) and their own increasing age and infirmity, the ladies had taken refuge in the West Tower, in what had been an ante-room connecting the great enfilade of state rooms on the southern facade with the kitchens.

Its round walls were hung with tapestries which Guy suspected had been chosen more for their capacity to exclude draughts than for their artistic content, for they mainly depicted people holding heads: Judith that of Holofernes, Salome of John the Baptist and St Jerome of a dismembered stag. The Meissen-tiled stove was unlit; dust lay on the carved arms of the vast chairs fashioned, it seemed, for the behinds of mountain ogres — but the condescension and graciousness of the ladies was absolute.

‘Welcome to Pfaffenstein, Herr Farne. We trust you found your journey enjoyable.’

Guy, kissing the extended hand and replying suitably, noticed with pleasure that the Duchess spoke what was called ‘Schönbrunner Deutsch’, a dialect which the high nobility shared with the cab drivers of Vienna. And indeed both ladies had been attendant on the Emperor Franz Joseph’s family in the palace of Schönbrunn outside Vienna where the gruelling Spanish ceremonial, the staggering absence of lavatories and the indifferent food had proved an excellent preparation for their present way of life.

Refreshment was offered and refused, the necessary courtesies were exchanged. Then Guy, whose German was fast and fluent, came to the point.

‘You will know already that I would like to buy Burg Pfaffenstein. My solicitors have mentioned the terms?’

The Duchess inclined her head. ‘They are fair,’ she conceded, ‘and we are willing. But as I have already informed your secretary, for a final decision we are awaiting a reply from Putzerl.’

Hearing the name, the pug shot like a squeezed pip from his golden cope and began to run round the room yapping excitedly, causing Guy to exchange an apprehensive glance with his secretary. If Putzerl was the name of the little dog they were in trouble.

The danger passed. For Putzerl, as the ladies now explained, was the great-niece in Vienna, more precisely the Princess of Pfaffenstein and (her mother having been an archduchess) of quite a few other places, and now the sole and legal owner of the castle with its dairies, sawmills, brewery, villages, salt-mine (now defunct) and 56,627 hectares of land.

‘Because, you see, when her father went off to fight he managed to break the entail on the male heir and a great fuss it was. He had to go and see poor cousin Pippi in the end,’ said the Margravine.

‘But we’re certain she’ll agree. She’s been urging us to sell. Putzerl is extremely modern,’ said the Duchess. ‘And of course the money will be invaluable for her dowry because poor Maxi really doesn’t have a kreutzer to bless himself with.’

The dizzying capacity of the Austrians to refer to absolutely everybody by some appalling diminutive or nickname, which Guy had forgotten, now returned to his mind. Having gathered that cousin Pippi was Pope Pius XV, he was now informed, though he had been careful not to ask, that Maxi (alias Maximilian Ferdinand, Prince of Spittau and Neusiedel) was the young man they had picked for Putzerl to marry, there being — owing to the cruel war and the sordid revolutions in various places which had followed it — quite simply no one else.

‘The Gastini-Bernardi boy would have done quite well, actually,’ said the Duchess, on whom the thought of Maxi seemed to be working adversely. ‘But he’s dead. And I must say there always seems to be cholera in Trieste.’