A few minutes after she had gone Inspector Burden came in. He had heard the story downstairs but had not entirely believed it. It was the part about putting another baby in Karen’s place that he couldn’t believe, he told Wexford. He hadn’t either, said Wexford, but it was true.

‘You can’t think of a reason why anyone would do such a thing,’ said Burden. ‘You can’t think of a single reason why even a mentally disturbed person would do such a thing.’

‘I suppose,’ said Wexford, ‘that by “you” you mean yourself or “one” because I can think of several reasons for doing it. First of all. you’ve got to take some degree of mental disturbance for granted here. Well-adjusted normal people don’t steal other people’s babies, let alone exchange them. It’s going to be a woman. It’s a woman who’s done it because she wants to be rid of that particular child, yet she must have a child. Agreed?’

‘Right,’ said Burden. ‘Why?’

‘She has to show it to someone else,’ Wexford said slowly, as if thinking aloud, ‘someone who expects to see a baby nearer in age and appearance to Karen Bond than to young Ginger, or who expects a baby of Karen’s sex. She may be a woman who has several sons and whose husband was away when the last one was born. She has told him he has a daughter, and to bear this out because she’s afraid of him, she has to have a girl to produce for him. On the other hand, she may not be married. She may have told a boy friend or ex-boy friend the child is younger than it is in order to convince him of his paternity.’

‘I’m glad you mentioned mental disturbance,’ said Burden sarcastically.

‘She may simply be exhausted by looking after a child who screams incessantly – young Ginger’s got a good pair of lungs – so she exchanges him for a baby she believes won’t scream. Or she may have been told that Ginger has some illness or even hereditary defect which frightened her so she wanted to be rid of him, but she still has to have a baby for her husband or mother or whoever to see.’

Burden seemed to be considering this inventiveness with reluctant admiration but not much conviction. He said, ‘So what are we going to do about it?’

‘I’ve taken everyone in the place off what they were doing and put them on to this. We’re getting on to all the hospitals and GPs, the Registrar of births, and the post-natal and baby clinics. I think it has to be someone local, maybe even someone who knew the pram would be there because she’d seen it there before.’

‘And seen the baby who was in it before?’ asked Burden, quirking up an eyebrow.

‘Not necessarily. A pram with a cat net over and whose occupant can’t be seen implies a very young baby.’ Wexford hesitated. ‘This is a hell of a lot more worrying,’ he said, ‘than a run-of-the-mill baby-snatching.’