‘But if it wasn’t Channing I saw, then who was it?’ Dorothy protested feebly. ‘There isn’t anyone else.’

‘There isn’t anyone else to be the murderer either,’ Rosemary pointed out.

‘What about Mr Anderson and Miss Davis? I saw them carrying the body upstairs between them, like a sack of coal!’

Rosemary gave her a withering look.

‘Well, of course! That’s what staff are for, isn’t it? Fetching and carrying and suchlike tasks may safely be entrusted to them, but never murder. That’s an absolutely fundamental principle. Otherwise what possible interest could the solution have, for heaven’s sake? Being killed by a servant is a fate of no more interest than being run over by a tram. No, no, the murderer must be someone like us, someone who matters.’

Dorothy threaded the wool on to her needles again and began to form the first stitches.

‘Yes, but there isn’t anyone else,’ she repeated. ‘Don’t you remember? We were all gathered here in the lounge.’

‘All except you,’ murmured Rosemary.

Dorothy’s hands became still.

‘What do you mean?’

‘I am merely pointing out that you are the only one who doesn’t have an alibi,’ Rosemary replied. ‘You left the lounge under the pretext of going to powder your nose shortly before the attack occurred, and returned immediately afterwards to stage an extremely convincing display of hysteria.’

Dorothy laughed and resumed her knitting.

‘Oh rubbish! What possible motive could I have?’

‘One can always invent a motive,’ Rosemary sniffed.

‘You might be the sultry Latin temptress with whose affections Channing, alias Randolph Fitzpayne, trifled in the course of his sojourn in Patagonia and who subsequently followed him to England intent on exacting revenge.’

Dorothy glared at her.

‘Honestly, Rose! Do I look like a dago?’

The door was opened by a lanky man in his mid-forties wearing a blue blazer and white flannel trousers. His long florid face rose to a mat of slicked hair which had receded to the centre of his skull. Holding the door ajar, he wheeled in a metal trolley supporting a large teapot and a pile of cups and saucers.