J turned from Patrick to her, as if to lecture the new girl in the class. ‘By delivering them informers, of course. Touts, enemies within, traitors.’

‘Delivering?’

‘Yes.’

‘Meaning?’

‘For God’s sake. Giving Imam Ali Baba the bad news that little Baba Ali has been working for the other side. Of course, he’s not delivering any little Baba Ali’s actually working for the other side – because that’s our side, isn’t it? And he’s working for us.’

‘Then who is he delivering to them?’

‘Up to him. As long he’s protecting ours.’

‘Did he ever have to deliver any of “our” actual guys to maintain his credentials with them?’

‘Come on, woman, don’t expect me to answer that.’

‘OK,’ said Sara, not bridling. ‘He “delivers” a little Baba Ali. What happens next?’

‘That’s between Kareem and his jihadi mates.’

‘What if jihadi mate asks Kareem to get rid of little Baba Ali? Or Kareem decides that might be the thing to do. Mete out justice on the spot.’

‘That’s down to him. Nothing to do with HMG.’

‘Though HMG gave him his contract,’ said Sara. ‘And his indemnities.’

‘Yes,’ said J. ‘That was Isobel’s call, not mine. But don’t be so legalistic. Just a bit of paper.’

‘I don’t think so,’ said Sara as quietly as she could against the shrieking wind.

J looked towards the shore again. ‘I won’t discuss that so don’t waste time.’

‘But you took one of the copies.’

‘So you say.’

‘Can I at least ask what you did with it?’

‘No you fucking well can’t. Move on,’ growled J. ‘But if you seriously think I’d ever have allowed my copy of that to see the light of day…’ He allowed the thought to linger.

‘OK,’ continued Sara, ‘the Blackburn files. Why are they significant?’

J chuckled hoarsely and spat into the sea. ‘You must have worked that one out.’

Sara recalled what Morahan had been told by Sayyid. ‘The inception? The tip of the iceberg?’

‘Hooray. Yes – despite the silly words. Pull on the thread, find the ball of wool.’ He stopped again to cough. ‘It was the first op. You don’t get any bloody rehearsals. Had to succeed.’

‘Succeed?’

‘Yes, prove his bona fides to both sides. Us, though we were sure of him. More importantly them. The jihadists. Expose an informer for them.’

‘How did Blackburn end?’

‘You don’t need to know that.’

‘OK, I’ll put it another way. Was the contract a means that justified the ends?’

‘Careful,’ said J, ‘you’re on the cliff edge.’ Sara kept silent, waiting for him. ‘As far as I was concerned – and for as long as I was there – this was a legitimate intelligence operation which brought results.’

‘What results?’