She took off her hat and threw it on the floor.

Bending her head, she went into the fireplace and began to climb. When she reached the top, she let out a strangled sob because her way was blocked by the chimney pot. Standing on the last rung, she stretched her arms up and pushed sideways with manic strength. The pot gave a little. She pushed harder until it gave and fell onto the roof and began to roll down to the edge.

* * *

Kerridge had just arrived with police officers when they heard a rumbling sound and a crash.

One of the policemen ran outside and then came running back. ‘It’s a chimney pot, sir, fallen off the roof.’

‘The library chimney,’ said Harry, who had just joined them wearing one of Lord Glensheil’s suits. ‘She might have escaped that way.’

They unlocked the library door. The maid’s hat lay in front of the fireplace and a final cascade of loose soot came falling down the chimney.

Thomson knew that the house next door was empty, the owners having gone to the country. She smashed the lock on a back door with a rock and let herself in. Far above her, she could hear the police searching the roofs.

She stripped naked in the kitchen and scrubbed herself clean at the sink. Then, still naked, she ran upstairs and into a lady’s bedroom. Quickly, she put on underclothes, gown and hat. She found a reticule and transferred the contents of her own sooty one into it.

She ran from room to room, ransacking the drawers and picking up as many portable valuables as she could. With a sigh of relief, she found a bag of guineas carelessly left on the bedside table in the master bedroom. She also found a spare set of keys, which by their size she guessed were for the front door.

Thomson walked down to the front door. She picked a parasol out of the stand by the door and took a deep breath. Unfurling it to hide her face, she unlocked the front door, locked it behind her, and strolled down the street. She hailed a cab at the corner.

‘Where to?’ asked the cabbie.

‘I’ll let you know. Just drive on.’

Kerridge and Harry went to St Stephen’s Tavern that evening to worry over this new development.

‘It’s a pity Lady Glensheil did not remember that the neighbours were away from home until hours later,’ said Kerridge. ‘A sooty woman running around London would have been easy to find, but there were all the signs that she had washed herself and stolen clothes.’

‘Do you think it is possible she is a murderess?’ asked Harry. ‘Might Jones be telling the truth?’

‘It’s hard to believe. We never even thought of her. What we should have considered was the oddity of a seemingly respectable lady’s maid taking a post with a well-known tart. It’s a class thing and I fell for it. Me! If she had been some slattern from the East End, I would have been suspicious.’