Smith Berry sat behind his desk with the chief secretary to his right. Waters, the former RIC man whom Swallow had previously encountered at Mallon’s house, sat to his left. Unusually, there were no clerks or secretaries present to take notes. The turf fires that normally blazed in the two grates were out. Swallow surmised that the trio had not been in the office very long, but that they had held earlier conversations elsewhere.

‘Sit down,’ Smith Berry commanded.

Swallow and Mallon took the two chairs indicated in front of the desk.

‘Mr Mallon, you know the chief secretary, Sir Arthur Balfour, of course,’ Smith Berry said.

‘Of course. Good evening, sir.’

Balfour nodded in recognition, almost imperceptibly. Swallow was not introduced. A mere detective inspector was the beneath the notice of Her Majesty’s Chief Secretary for Ireland, he knew.

‘Mr Mallon,’ Smith Berry said icily, ‘you have utterly overstepped your authority in detaining Major Nigel Kelly, a senior officer of my department, and a gentleman I should add, personally selected for his duties in Ireland by the chief secretary himself. Mr Balfour’s presence here is earnest, as I would hope you understand, of the gravity of the situation in which you have placed yourself.’

Mallon looked oddly relaxed, Swallow thought. He had observed this technique before in challenging encounters. It involved absolute discipline and a refusal to respond emotionally to whatever might transpire. When the chief of detectives spoke, his voice was even and calm.

‘Mr Smith Berry, Major Kelly is in lawful custody and is to be charged with murder of Helena Moyles, alias Helen or Ellen Byrne, alias Nellie Sweet. I’m sure the chief secretary understands that it is my duty to investigate serious crimes, of which murder is, of course, the most serious, and to bring to justice those towards whom the evidence of responsibility is pointing.’

Smith Berry snorted in annoyance.

‘Major Kelly is not guilty of any murder, Mr Mallon. And if you had any sense of your wider duty you would have reported to me before taking any action against a senior and valued officer of my department.’

‘You will be aware that I sought twice to meet with you over the past two days, sir,’ Mallon countered, ‘and on both occasions the message came back that you were otherwise engaged.’

Swallow saw Smith Berry wince slightly. He believed he saw Balfour’s eyes flicker briefly as the riposte was delivered.

‘Do not be disingenuous with me, Mr Mallon,’ Smith Berry said. ‘I do not believe, even if I had been able to make time to see you, that you would have informed me of this . . . proposed outrage.’

‘It is true I wanted to discuss a number of things, sir, but I would never fail to inform you fully on matters within your purview.’

It was a skilful answer.

Balfour spoke for the first time.