Silas Gaunt had inherited Whitelands from his father, but Silas had never been a farmer. Even when he left the Department and came to live here in retirement, he still let his farm manager make all the decisions. Little wonder that Silas got lonely amid his six hundred acres on the edge of the Cotswolds. Now all the soft greenery of summer had gone. So had the crisp browns of autumn. Only the framework of landscape remained: bare tangles of hedgerow and leafless trees. The first snow had whitened rock-hard ridges of the empty brown fields: crosshatched pieces of landscape where magpies, rooks and starlings scavenged for worms and insects.

Silas had had few guests. It had been a hermit's life, for the conversation of Mrs Porter, his housekeeper, was limited to recipes, needlework, and the steadily rising prices of groceries in the village shop. Silas Gaunt's life had revolved round his library, his records and his wine cellar. But there is more to life than Schiller, Mahler and Margaux, which trio Silas claimed as his 'fellow pensioners'. And so he'd come to encourage these occasional weekend house parties at which departmental staff, both past and present, were usually represented along with a sprinkling of the artists, tycoons, eccentrics and weirdos whom Silas had encountered during his very long and career.

Silas was unkempt; the wispy white hair that made a halo on his almost bald head did not respond to combs or to the clawing gesture of his fingers that he made whenever a strand of hair fell forward across his eyes. He was tall and broad, a Falstaffian figure who liked to laugh and shout, could curse fluently in half a dozen languages, and who'd make reckless bets on anything and everything and claimed – with some justification – to be able to drink any man under the table.

Billy and Sally were in awe of him. They were always ready to go to Whitelands and see Uncle Silas, but they regarded him as a benevolent old ruffian of whose sudden moods they should constantly be wary. And that was the way I saw him myself. But he'd had a fully decorated Christmas tree erected in the entrance hall. Under it there was a little pile of presents for both children, all of them wrapped in bright paper and tied neatly with big bows. Mrs Porter's doing no doubt.

Like all old people, Silas Gaunt felt a need for unchanging ritual. These guest weekends followed a firmly established pattern: a long country walk on Saturday morning (which I did my best to avoid), roast beef lunch to follow, billiards in the afternoon, and a dress-up dinner on Saturday evening. On Sunday morning his guests were shepherded to church and then to the village pub before coming back to lunch which was locally obtained game or, failing that, poultry. I was relieved to find that duckling was on the menu this week. I did not care for Silas's selection of curious little wild birds, every mouthful with its portion of lead shot.

'Surprised to see Walter here?' Uncle Silas asked me again as he sharpened his long carving knife with the careless abandon of a butcher.

I had registered my surprise on first arriving, but apparently I'd inadequately performed my allotted role. 'Amazed!' I said, putting all my energies into it. 'I had no idea…' I winked at von Munte. I knew him even better than I knew Uncle Silas; once long ago he'd saved my life by risking his own. Dr Walter von Munte smiled, and even the staid old Frau Doktor gave the ghost of a smile. Living with extroverted, outspoken Silas must have come as something of a shock after their austere and tight-lipped life in the German Democratic Republic, where even the von in their name had been taken from them.

I knew that the von Muntes were staying there – it was my job to know such things. I'd played a part in bringing them out of the East. Their presence was, to some extent, the reason for my visit, but their whereabouts was considered a departmental secret and I was expected to register appropriate surprise.

Until a few short weeks ago this lugubrious old man had been one of our most reliable agents. Known only as Brahms Four he'd supplied regular and carefully selected facts and figures from the Deutsche Notenbank, through which came banking clearances for the whole of East Germany. From time to time he'd also obtained for us the decisions and plans of comecon – the East Bloc Common Market – and memos from the Moscow Narodny bank too. At the receiving end, Bret Rensselaer had built an empire upon the dangerous work of von Munte, but now von Munte had been debriefed and left in the custodial care of his old friend Uncle Silas, and Bret was desperately seeking new dominions.

Silas stood at the end of the long table and dismembered the duck, apportioning suitable pieces to each guest. He liked to do it himself. It was a game he played: discussing and arguing what each and every guest should have. Mrs Porter watched the cameo with an expressionless face. She arranged the pile of warmed plates, positioned the vegetables and gravy, and, at exactly the right psychological moment, brought in the second roasted duckling. 'Another one!' said Silas as if he hadn't ordered the meal himself and as if he didn't have a third duckling in the oven for extra portions.

Before pouring the wine, Silas lectured us about it. Chateau Palmer 1961, he said, was the finest claret he'd ever tasted, the finest perhaps of this century. He still hovered, looking at the wine in the antique decanter as if now wondering whether it would be wasted on the present company.

Perhaps von Munte sensed the hesitation for he said, 'It's generous of you to share it with us.'

'I was looking through my cellar the other day.' He stood up straight, looking out across the snow-whitened lawn as if oblivious of his guests. 'I found a dozen bottles of 1878 port down there. My grandfather bought them for me, to mark my tenth birthday, and I'd completely forgotten them. I've never tasted it. Yes, I've got a lot of treasures there. I stocked up when I had the money to afford it. It would break my heart to leave too much magnificent claret behind when I go.'

He poured the wine carefully and evoked from us the sort of compliments he needed. He was like an actor in that and many other respects – he desperately needed regular and earnest declarations of love. 'Label uppermost, always label uppermost; when you store and when you pour.' He demonstrated it. 'Otherwise you'll disturb it.'

I knew it would be a predominantly masculine lunch, a departmental get-together, Silas had warned me beforehand, but I still came. Bret Rensselaer and Frank Harrington were both there. Rensselaer was in his middle fifties; American-born, he was trim almost to the point of emaciation. Although his hair was turning white, there was still enough of the blond colouring left to prevent him looking old. And he smiled a lot and had good teeth and a face that was bony so that there weren't many wrinkles.

Over lunch there was the usual seasonal discussion about how quickly Christmas was approaching and the likelihood of more snow. Bret Rensselaer was deciding upon a place to ski. Frank Harrington, our senior man in Berlin, told him it was too early for good snow, but Silas advised Switzerland.

Frank argued about the snow. He liked to think he was an authority on such matters. He liked skiing, golfing and sailing, and generally having a good time. Frank Harrington was waiting for retirement, something for which he'd been strenuously practising all his life. He was a soldierly-looking figure with a weather-beaten face and a blunt-ended stubble moustache. Unlike Bret, who was wearing the same sort of Savile Row suit he wore to the office, Frank had come correctly attired for the upper-class English weekend: old Bedford cord trousers and a khaki sweater with a silk scarf in the open neck of his faded shirt. 'February,' said Frank. 'That's the only time for any decent skiing anywhere worth going.'