'A perfect marriage of artistic merit and factual accuracy,' said Hooper, proudly. 'This is merely a rough version, of course, hastily finished so that I could offer it as evidence. I'll use this as the basis for a much larger and more dramatic painting.'

'It could hardly be more dramatic,' opined Colbeck, scrutinising the work. 'You are a man of talent, sir. I congratulate you.'

'Thank you, Inspector.' He pointed to the three small figures in the foreground. 'I moved the ladies slightly but this is more or less the position they were in. Not that they stayed there for long, mark you. When that poor man suddenly dived over the parapet, Aunt Petronella jumped back as if she'd seen a ghost.'

Colbeck was surprised. 'She was your aunt?'

'Not mine – the boy's. At least, that's what I assumed. They were complete strangers to me but I always like to give people names if I include them in a painting. It lends a sense of familiarity.' He indicated each one in turn. 'This is Hester Lewthwaite – this is her son, Anthony – and here is his maiden aunt, Petronella Snark.' He gave a sly chuckle. 'I suppose that if you've preserved your virginity as long as she had, the sight of a man descending on you from a great height would be quite terrifying.'

Colbeck could not believe his good fortune. Ambrose Hooper had provided the best and most comprehensive piece of evidence he had ever received from a member of the public. It answered so many important questions and saved him so much time. He was pleased to note that Micah Triggs had been so observant. The victim did appear to have been thrown from the last carriage. He remembered his own description of the victim.