‘That’s the one. She came to us last week with a story of blackmail. Here it is in this file. I’ll tell you briefly what she said, but I’m afraid you’ll have to put up with one Madame X.’

‘Phoo!’ said Lord Robert.

‘She told us that a very great woman-friend of hers had confided in her that she was being blackmailed. Mrs H-H wouldn’t give this lady’s name so there’s your Mrs X.’

‘Um,’ said Lord Robert doubtfully. ‘Otherwise Mrs ’Arris?’

‘Possibly,’ said Alleyn, ‘but that’s the story and I give it to you as Mrs H-H gave it to me. Mrs X, who has an important and imperious husband, received a blackmailing letter on the first of this month. It was written on Woolworth paper. The writer said he or she had possession of an extremely compromising letter written to Mrs X by a man-friend. The writer was willing to sell it for £500. Mrs X’s account is gone into very thoroughly every month by her husband and she was afraid to stump up. In her distress (so the story went) she flew to Mrs Halcut-Hackett who couldn’t provide £500 but persuaded Mrs X to let her come to us with the whole affair. She gave us the letter. Here it is.’

Alleyn laid the file on Lord Robert’s plump little knees. Lord Robert touched his glasses and stared for quite thirty seconds at the first page in the file. He opened his mouth, shut it again, darted a glance at Alleyn, touched his glasses again and finally read under his breath:

‘If you would care to buy a letter dated April 20th, written from the Bucks Club addressed to Darling Dodo and signed M., you may do so by leaving £500 in notes of small denomination in your purse behind the picture of the Dutch funeral above the fireplace in the ballroom of Comstock House on the evening of next Monday fortnight.’

Lord Robert looked up.

‘That was the night the Comstocks ran their charity bridge-party,’ he said. ‘Big show. Thirty tables. Let’s see, it was last Monday.’

‘It was. On the strength of this letter we saw the Comstocks, told them a fairy-story and asked them to let us send in a man dressed as a waiter. We asked Mrs H-H to get her distressed friend to put the purse full of notes, which we dusted with the usual powder, behind the Dutch funeral. Mrs H-H said she would save her friend much agony and humiliation by doing this office for her.’ Alleyn raised one eyebrow and bestowed a very slow wink upon Lord Robert.

‘Poor thing,’ said Lord Robert. ‘Did she suppose she’d taken you in?’

‘I don’t know. I kept up a polite pretence. Our man, who I may say is a good man, attended the party, saw Mrs H-H tuck away the bag, and waited to see what would happen.’