Dan and I hurried over to the uniformed police officer who was guarding the scene. ‘I’m DI Rahman. This is DS Maguire. Limehouse.’ While he added our names to the log, I told him about the woman’s call to 999. ‘She thinks her husband’s been murdered in the fire. Sounds extremely scared.’

He pointed at a thick-set man with a shaved head, who was standing inside the cordon next to a digger, giving orders to a team of fluorescent-jacketed men with brooms and shovels. ‘Simon Chapel is the fire crew manager. You’ll have to speak to him.’

Dan and I made our way over. An army of personnel had cleared people away and begun conducting operations. Uniformed police, fire-fighters, fire investigation officers and CSIs all weaved around each other. A high-volume pump was in front of the shop, and a water management unit and aerial platform were standing by. Firefighters were a mass of blue uniforms, and their yellow stripes and helmets stood out like beacons. Some were transporting ladders and breathing apparatus. Others were holding jets and unravelling reels. A few charred window frames were still in place. One small pane remained, jagged and angry. Black and white tendrils of smoke were still seeping out of openings, but it was hard to tell whether these were fumes or steam. Water streaked the walls of the building, staining the yellow brickwork.

I introduced Dan and myself to Simon, and told him about the woman’s phone call.

He groaned. ‘Someone knew what they were doing, I can tell you that, but I hope she’s wrong.’ The man’s tone was clipped and the veins on his face and scalp bulged with concern, knowing he held people’s lives in his hands, and that his decisions were critical. ‘As soon as the building’s safe, we’ll get someone in.’

‘Any signs of anyone in there?’ The woman on the recording had sounded terrified. Not a bit like a crank caller.

‘We can’t get close enough to see. The speed the flames tore through the floors, and the fumes in there . . . ’ He was shaking his head. ‘If anyone was inside, they won’t have survived those temperatures or the smoke. They had an extraction system on the ground floor. Add timber flooring to that, wooden joists, lathe and plaster, and it’s all increased the speed the fire spread. Not seen a blaze like this for several months.’

‘Any indication it was deliberate?’ A sinking feeling was stealing over me. The caller had refused to give the emergency services operator her name, so we couldn’t be certain she was connected to the premises.