‘That is your privilege, Minister,’ Tweed replied equably.

Paula frowned. She was taken aback. She had expected Tweed to thunder back. Especially after his combative mood at Park Crescent.

‘I’m glad you appreciate that,’ Warner commented, his voice several decibels lower.’

‘Minister,’ Tweed leaned forward, his manner calm, ‘I was hoping – still believe you will agree – that we can cooperate in this desperate situation. I look forward to a state of collaboration between us. We do have a common enemy. With our combined forces we will defeat that enemy.’

Warner was taken aback. He removed his pince-nez, exposing his hawk-like nose. He took out a cloth, polished the pince-nez, perched them back on the bridge of his nose.

‘There is a lot in what you have just said,’ he agreed, his voice now normal, verging on the polite.

Paula suddenly caught on. Tweed was being very clever. Realizing Warner was worried about his position in the Cabinet, he had just been provided with the perfect way to present the development to his colleagues.

Tweed has explained to me the meaning of the document. He says the meaning of the document is to encourage collaboration between all the security services.

‘May I make a suggestion about one way forward?’ Tweed asked.

‘Certainly, my dear chap. I am all ears.’

‘My Whitehall visitor had heard a rumour that Tolliver is now head of Special Branch.’

‘That is so. With Buller disappearing I had to appoint someone to run that vital service. Tolliver is very able.’

‘For some time,’ Tweed continued, ‘Special Branch officers have worn a kind of uniform – camel-hair coats. So much so that villains recognize them. I suggest a large number of Special Branch officers flood the main areas of Central London. Buckingham Palace, St Paul’s, Canary Wharf, along the Thames Embankment.’

‘What a brilliant, idea!’ Warner smiled, as always an insincere smirk. ‘I’ll get that organized the moment you leave.’

‘Then there are communications,’ Tweed went on. ‘Whoever is planning this attack has to communicate. It’s possible he does so with radio. You have a section which monitors certain radio transmissions. They could be asked to listen for unusually heavy traffic. You have code-breakers. One is sitting next to Miss Grey.’

‘You are full of good ideas, even if we are already listening. But I will direct that section to listen for any unusually heavy traffic. Tweed, I think it’s time for us to seal our pact with sherry.’

Tweed stood up. ‘Thank you for the suggestion. Another time, perhaps. I have to get back to Park Crescent.’

‘Of course. Eva will show you out. I must deal with your suggestions urgently…’

They had left the study. The door was closed when Eva moved close to Tweed. She squeezed his arm as she whispered.

‘I can see even more now why you hold the job you do. I’d never have dreamt you could turn him round the way you did.’

‘The first rule,’ Tweed told her, ‘is self-control. You can then adapt your tactics to whatever situation confronts you.’

‘I’m still stunned…’

They had left the building and were walking to where Newman had parked his car when Paula squeezed Tweed’s arm.

‘I’m wondering how Marler will get on at Carpford.’