‘It’s not enough,’ said Lesley. ‘One: they’re already generating leads over WITNESS A, including the possibility that he was wearing a mask. Two: you could have got all that information from the video.’

‘They won’t know I had access to the video.’

‘Peter,’ said Lesley. ‘It shows someone’s head being knocked off. It’s going to be all over the internet by the end of the day, and that’s if it’s not on the ten o’clock news.’

‘Then I’ll generate more leads,’ I said.

‘You’re going to go looking for your ghost?’

‘Want to come?’

‘No,’ said Lesley. ‘Because tomorrow is the most important day of the rest of my career, and I am going to bed early with a cocoa and a copy of Blackstone’s Police Investigator’s Workbook.’

‘Just as well,’ I said. ‘I think you scared him away last night, anyway.’

Equipment for ghost hunters: thermal underwear, very important; warm coat; thermos flask; patience; ghost.

It did occur to me quite early on that this was possibly the most absurd thing I’d ever done. Around ten I took up my first position, sitting at an outdoor table of a café, and waited for the crowds to thin out. Once the café closed I sauntered over to the church portico and waited.

It was another freezing night, which meant that the drunks leaving the pubs were too cold to assault each other. At one point a hen party went past, a dozen women in oversized pink t-shirts, bunny ears and high heels. Their pale legs were blotchy with cold. One of them spotted me.

‘You’d better go home,’ she called. ‘He’s not coming.’

Her mates shrieked with laughter. I heard one of them complaining that ‘all the good-looking ones are gay’.

Which was what I was thinking when I saw the man watching me from the across the Piazza. What with the proliferation of gay pubs, clubs and chat rooms, it is no longer necessary for the single man about town to frequent public toilets and graveyards on freezing nights to meet the man of their immediate needs. Still, some people like to risk frostbite on their nether regions – don’t ask me why.

He was about one-eighty in height – that’s six foot in old money – and dressed in a beautifully tailored suit that emphasised the width of his shoulders and a trim waist. I thought early forties with long, finely boned features and brown hair cut into an old-fashioned side parting. It was hard to tell in the sodium light but I thought his eyes were grey. He carried a silver-topped cane and I knew without looking that his shoes were handmade. All he needed was a slightly ethnic younger boyfriend and I’d have had to call the cliché police.

When he strolled over to talk to me I thought he might be looking for that slightly ethnic boyfriend after all.