'Yes. I did know.'

'A daughter.'

'Sally had an aunt in Hungerford who seemed to think she needed to be kept informed about that sort of thing.'

'When you'd rather she'd been allowed to forget the Halls.'

'What about Oliver Hall? He didn't register on Aunt's radar. Banker, wasn't he?'

'Not sure, technically. Stockbroker. Financial consultant. Something like that. A money man. Retired to Jersey, I gather. That must make him a mega-money man. None of which brings his daughters back to him, of course. Also remarried. But no more children.'

'And the son?'

'Went to live with his father after his mother remarried. That was before his father pulled the same trick. Then…' Sharp shrugged. 'I never had any cause to find out. Until now.'

'None of these people are going to want to talk to us, George.'

'I can be very persuasive. You'll just have to follow my example.'

'Who else do you intend to contact?'

'The other witnesses. If they're still in the land of the living. Collingwood was seventy-odd and shaky. I'll check, but I'm not optimistic. Nevinson's a better bet. Unless one of the stones has keeled over on top of him, I guess he'll still be hanging around Avebury. He and his sister lived with their mother on the council estate at Avebury Trusloe – where they put the villagers whose houses were pulled down in the Fifties. Aside from nature taking its course where the mother's concerned I can't see much having changed there.'

'But a nutter, by your reckoning.'

'Sending me a letter made up of old Junius quotes could be right up his street.'

'You reckon?'

'I don't know. It's a thought. Could Nevinson be Griffin?'

'Nevinson?'

The fellow had been there, at Avebury, with Umber, standing helplessly by the body of Miranda Hall, while they had waited for the emergency services to arrive. Customers from the Red Lion had joined them. Everyone, including those who had not seen the event itself, had been shocked, talking in soft, distracted undertones. The landlady had taken Sally and Jeremy into the pub, leaving Umber and Nevinson out on the road, watching the blood soak slowly through the blanket that someone had draped over poor dead little Miranda. They must have spoken to each other. They must have done. But Umber could remember nothing of what they had said.

'He can't be Griffin. I'd have recognized his voice.'

'Sure?'

'Of course. I'd have been bound to. It was only two days since I'd spoken to Griffin.'

'OK. Fine. But that leaves us with a problem.'

'Who is Griffin?' Umber mused, versifying the words in the style of Who is Sylvia? 'What is he?'

Umber left Sharp dozing in the passengers' lounge during the ferry crossing and went on deck to watch the patchy moonlight skittering across the Channel. It was a still, cold night. Dover glowed amber ahead, Dunkirk astern. He found himself remembering his one and only conversation with the mysterious Mr Griffin, replaying it in his mind, as close to word for word as he could manage, so close, indeed, that he could almost swear they were the words, exact and verbatim.

Saturday afternoon, 25 July 1981. Umber was watching cricket on the television. He heard the telephone ring, but left his mother to answer it. Then she called to him, 'It's for you, David.' He watched one more delivery before ambling out into the hall.

'Hello?'

'David Umber?'

'Yes.'

'You don't know me, Mr Umber.' The voice sounded silken, muffled, faintly effete. 'My name is Griffin.'

'Right.'

'I'm in Oxford.' The phrasing somehow implied that Oxford was not Griffin's normal stamping-ground. 'I've heard about your… Junian researches.' This phrase too seemed loaded. The use of the adjective Junian suggested close familiarity with the letters and the controversy over their authorship.

'How did you -'

'I have something that may interest you. Something germane to your research.'

'Oh yeah?'

'It's a rather unusual copy of the 1773 edition of the letters.' That, as Umber was well aware, meant the second edition, incorporating an index and table of contents, for which Junius had told Woodfall he would wait before his bespoke copy was produced. 'Vellum-bound and gilt-edged. Very handsome.'

'Vellum-bound… and gilt-edged?' Umber could not believe his ears.

'Quite so. Complete with an illuminating and more than somewhat surprising inscription.'

'You're having me on.'

'No. I'm in earnest, I assure you.'

'But… you can't be.'

'I understand your incredulity. But I speak the absolute truth. I have what I describe. Would you like to see it?'

'What does the inscription say?'

'I can't discuss that over the telephone. If you're interested, I think we should meet.'

'Of course I'm interested.'

'Well, then?'

'I can come up to Oxford tomorrow.'

'This is no business for the sabbath.' Once again there came a hint of other-worldliness. It struck Umber that his caller sounded more like a man of the eighteenth century than the twentieth. 'Would Monday suit?'

'Sure.'

'But not Oxford. There are too many eyes and ears in this city. Do you know Avebury?'

'Yeah. Sort of.'

'Let's meet at the village inn. The Red Lion. I'll be there at half past twelve.'

'I can make that.'

'Good. It won't be a wasted journey. I think I can promise you that.'

'Look, Mr Griffin, I -'

'Until Monday.'

With that the line went dead.

And it had stayed dead for twenty-three years, subsumed and forgotten in the wake of the tragedy that had struck at Avebury two days later, engulfing all those who had been there to witness it. 'It won't be a wasted journey. Griffin had said. 'I think I can promise you that.'

Dover in the small hours of a chill March morning did not make for a gala homecoming. Sharp's doze aboard the ferry had left him taciturn and liverish. Umber was tired and dispirited. Leaving Prague suddenly felt like a huge mistake. Little was said as they followed the signs for the motorway and headed towards London.

Sharp stopped at a service area near Maidstone and announced he would be stretching out in the back of the van for the rest of the night. Umber retreated to the cafeteria.

Come dawn Sharp was as bright as a lark, tucking into a full English breakfast after a wash and a shave in the service area toilets. Umber was bleary-eyed and mentally drained. He did not even ask where they were going next. Somewhere between Maidstone and the M25, he fell asleep.