A stand of umbrellas, brightly coloured, catches Ruby’s eye as they arrive at their floor. The stand is unattended, so she picks one up as she passes and hooks it over her arm. The blue matches the colour of her best French coat. The colour of a cloudless sky when you walk through a park on a summer’s day. She bought it the other day, she decides. Monday, or was it last week? She can’t recall now and she’s lost the receipt.

They make their way to the main room. The area is busy, but the atmosphere is hushed and reverent. Women of all ages mill around touching the coats, stroking them, bowing to inspect the quality of the cuffs and buttons, squeezing the shoulders before asking to try them on. This is why stores like Debenham and Freebody are so successful: they allow a customer to decide what she wants to examine, what she wants to wear. They give her choice and credit her with intelligence and discernment.

They also enable someone to lift with relative ease.

Ruby strokes a fur wrap. Silver fox, lined with grey silk. Not her personal style, and they are not in the store to take coats or wraps today.

‘What do you think?’ she asks Edith, who is admiring the fur collar on a long coat of the finest black wool. ‘A bit old-fashioned?’

Edith plays the game. ‘You’ll look like my grandmother.’

‘Shame. It feels lovely and soft.’

The conversation causes another woman to turn her head. She is wearing a dull grey coat and a very ordinary, wide-brimmed navy blue felt hat that doesn’t fit very well. She is middle-aged, but not old. She is trailing a hand rather listlessly down the arm of a garment that she is unlikely to buy – the sort of coat one might wear out in a motor car. She doesn’t seem like the adventurous, driving-out-for-the-day sort.

Ruby smiles at her and leans into Edith.

‘Come on,’ she says. ‘I’m done with this, let’s go elsewhere.’

She squeezes Edith’s wrist twice, quickly and sharply, and Edith nods. She will leave now that she’s been given the agreed signal, and the two of them glide away, out of the main room and back to the store’s central staircase.

‘They’re using detectives now?’ Edith mutters, limping down the stairs, heels clacking on the marble. She scowls at Ruby, her feet feeling the blisters.

Ruby checks the stairs behind her, making sure that they are not being followed.

‘She looked like one. The woman with the navy blue hat. Didn’t you see her? There was just something about her.’

‘No, I didn’t see her.’ Edith takes a surreptitious glance over her shoulder. ‘More places are using them now; I suppose we should have expected it.’

‘We should warn the others.’