‘She formed the habit of perpetrating rather silly jokes on people. This was an attempt to command attention. She used to let her performances remain anonymous. Now she usually brags about them. That, of course, is a good sign.’

‘It’s an indication, at least, that she’s not the author of the more recent practical jokes on her grandfather.’

‘I agree.’

‘Or the author of the anonymous letters.’

‘That, I should have thought,’ said Miss Able patiently, ‘was perfectly obvious.’

‘Who do you think is responsible for the letters?’

‘I’ve told you, I can’t make snap decisions or guesses.’

‘Couldn’t you just unbend far enough to have one little potshot?’ he said persuasively. Miss Able opened her mouth, shut it again, looked at him with somewhat diminished composure and finally blushed. ‘Come!’ he thought, ‘she hasn’t analysed herself into an iceberg, at least.’ And he said aloud: ‘Without prejudice, now, who among the grown-ups would you back as the letter-writer?’ He leant forward, smiling at her, and thought: ‘Troy would grin if she saw this exhibition.’ As Miss Able still hesitated, he repeated: ‘Come on; who would you back?’

‘You’re very silly,’ Miss Able said, and her manner, if not coy, was at least very much less impersonal.

‘Would you say,’ Alleyn went on, ‘that the person who wrote them is by any chance the practical joker?’

‘Quite possible.’

He reached a long arm over the desk and touched the top sheet of the exercises. ‘They were written,’ he said, ‘on this paper.’

Her face was crimson. With a curious and unexpected gesture she covered the paper with her hands. ‘I don’t believe you,’ she said.

‘Will you let me look at it?’ He drew the sheet out from under her hands and held it to the light. ‘Yes,’ he said. ‘Rather an unusual type with a margin. It’s the same watermark.’

‘He didn’t do it.’

‘He?’

‘Tom,’ she said, and the diminutive cast a new light upon Thomas. ‘He’s incapable of it.’

‘Good,’ Alleyn said. ‘Then why bring him up?’

‘Patricia,’ said Miss Able, turning a deeper red, ‘must have taken some of this exercise paper over to the other side. Or…’ She paused, frowning.

‘Yes?’

‘Her mother comes over here a great deal. Too often, I sometimes think. She’s not very wise with children.’

‘Where is the paper kept?’

‘In that cupboard. The top one. Out of reach of the children.’

‘Do you keep it locked?’

She turned on him quickly. ‘You’re not going to suggest that I would write anonymous letters? I?’

‘But you do keep it locked, don’t you?’ said Alleyn.

‘Certainly. I haven’t denied that.’

‘And the key?’

‘On my ring and in my pocket.’

‘Has the cupboard been left open at all? Or the keys left out of your pocket?’

‘Never.’

‘The paper comes from a village shop, doesn’t it?’

‘Of course it does. Any one could buy it.’