‘Back seat,’ said a muffled voice. It seemed to be coming through some sort of box. ‘We will talk on the move.’ The driver was sporting a cap, thick-framed glasses, a checked scarf wrapped round the face and a high black polo-neck sweater which rose above the collar of a black leather jacket. Morahan had imagined Sayyid in an office suit and tie, his natural habitat a corridor of power – or, at least, of information. ‘It’s better you cannot see what I look or sound like,’ the distorted voice continued. ‘For you, I mean.’

‘I’m hardly experienced in these things,’ said Morahan.

‘I am not accustomed to giving senior judges classified documents.’

‘You’re acting in the public interest.’

‘There are not many in your position who would see it that way. They would have reported the approach and been done with it.’ Morahan noted the precision and lack of animation in his speech – more than just the product of the digital device. He was a man who chose his words carefully. ‘They are the innocents,’ Sayyid continued in his monotone, ‘who put a cuckoo in the nest.’

He drove along the Embankment at a steady thirty miles an hour, waiting at Chelsea Bridge for the filter light to change. He turned right across the river, passed bikers stopping for coffee and burgers at the night stall, and turned right again into Battersea Park where he drew up in the shadow of a clump of trees.

‘The young woman is on board, yes?’ he said, his head making a quarter turn.

‘Yes.’ Morahan stopped, wondering what Sayyid knew or didn’t know. One way to explore. ‘She’s gone North, following those files.’

No reaction, not a flicker. He passed a brown A4 envelope to the back. ‘Now that she has arrived, I can give you a third folder. It contains a photograph and an audio cassette. It will replay on your dictaphone.’ Morahan thought to ask how he knew what dictaphone he possessed but restrained himself. ‘With this information,’ continued Sayyid, ‘you will detect a link. When you think the time is right, let her see it – the sooner the better.’

Morahan hesitated; he wished to appear neither stupid nor over-eager. ‘A link that ends where?’

‘That’s for you and the woman to work out. As I told you, those files are the tip – and the beginning – of the iceberg.’

‘Continuing the metaphor,’ said Morahan languidly, trying to match Sayyid’s tone, ‘if the iceberg is man-made, who commissioned it? And controlled its size and temperature?’

‘Let us cut the metaphor,’ the voice snapped, ruffling the calm. ‘That is why I wanted to see you in person.’ Sayyid shuffled in his seat but didn’t turn. ‘Because that is what I do not know. There are people who think they know. But only one, possibly two, truly does.’

‘I find that hard to interpret.’