Bourne stared at it. He leant precariously over the broken wall and found he could touch it with outstretched hand. At the second attempt he managed to hold it and lift it dripping from the greasy water. Carefully he made his way back to the others, handed it up to them and climbed up after it.

Meredith turned it over in his hands. As far as Paul could see it was a small once-black deedbox, no more than ten inches by five inches by four. Its surface was roughened and reddened with rust. On its top was a ring, now rusted immovably to the top. Where there should have been a keyhole, a metal plate had been fixed to the side.

‘As far as I can see,’ Bourne said, ‘there are only two reasonable hypotheses. Either it existed in the house upstairs and fell into that cavity when the house collapsed during the fire or it already was in the cavity when the fire began.’

Meredith nodded.

‘Presumably the part of the wall you pushed into the water dislodged what was holding it down.’ He took a deep breath. ‘I suggest we get back to the cars and try to find some way of opening this. Whatever is in it may tell us which of your hypotheses is the correct one.’

The three men walked down the drive towards the car. The women stood by the television van looking towards them, obviously anxious because they had taken so long to reappear. They knew immediately by the expressions on the men’s faces that something had happened. Paul, unable to work on the box, told them what they had found while the other men brought out the van’s tool kit.

‘In the cellars?’ Joyce repeated. ‘But you searched the cellars. You didn’t find anything then.’

Carol, her face white with horror, looked at him.

‘You think the other wall was built to conceal them?’ Her eyes narrowed as he made no reply. ‘There’s something else, isn’t there?’

He nodded, swallowed bile as he remembered.

‘I’m not sure.’ But in his own mind he had no doubts.

‘Was it done recently?’ Ann asked, her voice higher-pitched.

‘Impossible to say at the moment. Dr Bourne wouldn’t commit himself. Said he had no forensic experience.’ He hesitated. ‘I think it happened many years ago.’ A vision of the tragic-faced girl in her turn of the century clothes rose before him. Carol looked at him.

‘Why do you think that?’

Quietly he told them of the appearance of the girl and of how she seemed to have drawn his attention to the cavity and its contents.