The picture she showed Cooper was crayoned with great care, but little subtlety. There were small children with stick arms and clothes of various colours, and there was a figure with a white beard and a red coat patting them on the head and offering them brightly coloured gifts. It was captioned ‘Fathr Chistmass.’

‘A bit early to be doing Christmas, aren’t you? It’s only just gone Bonfire Night.’

Helen laughed. ‘Yes, they do get confused sometimes.’

But somehow it didn’t look quite right. There was something wrong about Father Christmas’s costume. He looked like one of those cut-price Santas in the shops in Edendale at Christmas, with home-made suits and cotton-wool beards that never fit. Most of them would scare the kids to death, if they got too close. But these days, there was no touching allowed, not even by Santa. No ‘come and sit on my knee, little girl.’

Cooper thought of Warren Leach’s boys, their air of guarded distance, an instinctive wariness of strangers. There had seemed little innocence about the Leach place. He wondered what the two boys had seen or experienced in their lives that made them nervous of visitors.

He looked again at the drawing in his hands. It wasn’t the red jacket that made it look wrong. It was the trousers. Every child knew that Santa’s trousers were red, the same as his jacket. But Carly had changed crayons halfway through drawing her picture of Father Christmas and his presents. She had selected her new colour carefully – and it wasn’t a colour that a child of six would normally choose. It wasn’t bright or dramatic enough; it was too dull and adult somehow.

Yes, everyone knew Santas were dressed all in red. But this Santa had grey trousers.

The house was set deep into the hillside, below the level of the road. Its front door was at the foot of a steep, narrow flight of stone steps lined with wooden tubs and pots of wilted sweet peas, enclosed by a well of sheer walls and blocked-up windows. The remains of dead plants trailed down to the door, leaving patches of dark mould and slime on the steps, treacherous patches that would send an unwary postman hurtling to the bottom. Yet on the window ledge of the room above the road there was a single pelargonium in bloom, its red flowers gleaming against the grey curtain.

When Owen Fox answered the door, he appeared to be standing at the bottom of a deep hole. He looked as though he had been dozing; he was sleepy-eyed and half-dressed, and his beard and hair were tangled. When he saw Diane Fry standing on the steps above him, he pulled his dressing gown around his chest.

‘Do you want some help?’ he said. ‘I suppose you need my local knowledge again?’