Rose was aware of the bell-rope next to her chair. If only she could tug it, a servant would appear, and surely this whole household of servants wasn’t party to the murders.

‘What happened to Murphy? What happened to Mr Pomfret’s manservant? Did you kill him, too?’

‘I paid him to leave for Ireland. He was glad to accept. He didn’t know I’d killed Pomfret but I didn’t want him in that flat in case he found that photograph. I said I was looking after him out of kindness and to honour Pomfret’s memory.’

Rose put her hand to her forehead and swayed in her chair. ‘I feel faint,’ she said.

‘Then faint,’ snapped Angela.

Rose swayed in her chair nearer the bell-rope. Then, as if about to lose her balance, she seized the bell-rope.

The double doors of the drawing-room opened and a footman stared at the tableau and then retreated. Rose could hear him running down the stairs.

To her amazement, Angela, in her fixed concentration, had not even noticed.

But suddenly a voice shouted from downstairs, ‘We’ve got to get the police!’

Angela’s eyes widened and her finger tightened on the trigger.

Rose threw herself to one side, tipping her chair over onto the floor, just as the gun went off with a deafening report. The recoil jerked Angela backwards and she gave a howl of pain and dropped the gun.

Rose sprang up from the floor. She fell on Angela, screaming and clawing and biting, dragging her out of her chair while Angela fought to get the gun. Angela was wiry and strong. She rolled Rose under her and her bony hands encrusted with rings fastened around Rose’s throat.

And then Harry erupted into the room, followed by Becket and Daisy. They had met Daisy in the street as she was running to get help.

Harry seized Angela by her thin shoulders and jerked her off Rose. He turned and addressed the gawping servants clustered in the doorway. ‘Fetch something to tie her up!’

‘No,’ gasped Angela. ‘I am calm now. I will go quietly.’

Two policemen came into the room. ‘Arrest this woman for murder and phone Detective Superintendent Kerridge. We will follow you to the police station and make statements,’ ordered Harry.

Angela stood up and with a quaint dignity said, ‘I must take my medicine with me. I have a bad heart.’

‘Send a servant.’

‘No, I have it here, over in that desk.’

She went to the desk and took out a small bottle. She squared her shoulders. ‘Now, I am ready.’

Rose looked wildly at Harry but he stared back at her, his face a mask. The two policemen moved forward. ‘If you will come with us . . .’ one started to say. Angela twisted the cork off the bottle and tipped the contents down her throat.

‘In a moment,’ she gasped. Her face contorted and she clutched her neck. Then she held her stomach and moaned as she sank to the floor.