Hadley’s eyebrows lifted, but to his credit he took this in his stride. ‘My impression from Mr Eden-Summers was that this was a marriage more of convenience than of love. His family desired closer University ties for political reasons which elude me,’ said Hadley.

This would explain Eden-Summers’ slightly odd response to the news of Dillie’s death, I thought.

‘The pawning of the rings, however, casts a new light,’ continued Hadley, thoughtfully.

‘Of course, Miss Wyndham also accepted Leo Vitale’s ring and proposal,’ I offered. Holmes shot me a look of reproach. I wondered if he didn’t harbour an unusual bias towards the young scientist.

‘We know that, Dr Watson,’ said Hadley, smoothing his reddish moustache. ‘I arrested him on the basis of his shouted fight with the deceased on the night of her murder, apparently all about this ring. It was heard by several in the street near the Cross and Anchor – where, incidentally the girl had been hiding out.’

‘Yes, yes, Vitale is not beyond suspicion,’ agreed Holmes, ‘but I would not have let Eden-Summers off so quickly.’

Hadley looked uneasy at the thought. It struck me how odd it was that the Cambridge policeman was allowing the case to be led by a prisoner in his own gaol.

‘I feel certain that Eden-Summers will remain at his estate,’ said Hadley. ‘The Duke is incensed at the loss of the ring – apparently a family heirloom worth a small fortune.’

The pawnbroker Mr Flan must consider himself in luck, I thought. He knew all along the worth of Eden-Summers’ rather ostentatious ring and had vastly underpaid.

‘It may be found, along with Mr Vitale’s ring, at Piotr Flan’s pawnshop on the Cheltenham Road. Brought there by Deacon Peregrine Buttons.’

‘Good Lord!’ said Hadley, clearly surprised by this news.

‘If you will set me free, I will show you what I found in Buttons’ room. Miss Wyndham received her fatal blow there in a fierce battle. The signs are there to be read. But I had not finished my examination when Watson spotted Buttons on the Jesus Lock footbridge. You know the rest.’

‘Wright is a good man. He will find anything that is in the room.’

Holmes grimaced, the picture of frustration. ‘Nevertheless, doing so without me is a mistake.’

‘Perhaps, Mr Holmes, but you dug your own pit by escaping from custody earlier. Buttons is the most obvious suspect. His attempted suicide shows he is clearly deranged and racked by guilt. By several accounts he was utterly obsessed with the girl.’

As much as I had liked Buttons, I was beginning to agree with Hadley on this matter.

‘I understand from Professor Wyndham that it was young Buttons who brought you into the case,’ Hadley continued.

‘An argument against his guilt, would you not think?’ said Holmes.