‘Everything was fine. Thank you.’ Bourne turned to the other occupants of the room. ‘May I please remind you that Miss Parish has agreed to be kept in the dark regarding anything connected with what we’ve just heard. In fact, Ann, if you would be so kind as to leave the room . . .’

Good-naturedly, Ann Parish stood up. She smiled at Carol.

‘Don’t worry, Mrs Wilson, I’m used to being sent out of the room like a naughty schoolgirl. I must confess to being extremely curious about it all but Dr Bourne assures me it’s in a good cause and that he will reveal all at the proper time.’ At the door she paused. ‘I’ll get on with the dishes.’

Meredith rose. ‘I haven’t washed a dirty dish since we arrived, I’ll come with you.’

Carol thought: In pairs again – or is he keeping an eye on her to make sure she doesn’t listen at the door?

By now the camera had been switched off. Bourne re-emphasized the stricture on communicating with Ann.

‘No names of former inhabitants of the house, no history, no discussion of what we are doing. It’s vitally important – ’

The lounge door reopened. Meredith came in, with Ann close behind him. Her face was troubled. Meredith’s expression was unreadable.

‘I would like you all to come into the dining-room.’

Something in his tone of voice brought obedience without his listeners doing more than glancing questioningly at each other. He led the way across the dingy hall. They filed into the other room. Paul, entering after Carol, saw those who had preceded him glance round, then up. He heard gasps emitted from Joyce Mair and Jeremy Hunt. When he entered the big room he halted, bumping into Carol, who had stopped immediately she could see what the others had seen.

Each of the long, threadbare, mud-brown window curtains in the bay had been tied in a huge knot. Scattered over the faded carpet were scores of pieces of coal. The two big sideboard drawers had been placed under the table: into the gaps left by their absence, long cushions from the window seat had been stuffed. And on the table, in the middle, a four-foot-high tower had been erected of plates, cups, saucers, two milk-jugs and the coffee-pot, the last balanced precariously on top of the tall erection.

Meredith said quietly: ‘Bourne, you brought Ann and Miss Mair from the kitchen. Everything was normal then.’

It was not really a question but Bourne nodded. His eyes flicked over the company.

‘And we were all in the lounge. No one left.’

Pollard stared up at the coffee-pot.

‘So it must have been done while we were all together.’