‘There’s no evidence that the two attacks are related. Is your car in the exact position it was yesterday?’ When I nodded he said, ‘I’d be obliged if you’d leave it there for a couple of hours. Our forensic people will want to measure sight lines.’

‘That’s all right as long as I don’t get a parking ticket. How will measuring sight lines help?’

‘I don’t know,’ he said. ‘But in police work you go by the book, and the book says we measure sight lines. Police procedure goes by its own book, not by the lucky guesses of detective story writers. I haven’t read a detective story yet where the evidence would stand up in court.’ He pointed to my car. ‘I may have to testify and the defending counsel will say, “Superintendent Hanna, did you measure the sight lines?” and if I hadn’t, he’d say, “Why not?” and there’d be a big question left in the minds of the jury, irrespective of whether sight lines came into the evidence at all.’

‘So you measure sight lines,’ I said.

‘We do a lot of unnecessary work just to protect ourselves. There are too many people ready to think ill of the police.’

We walked down the alley towards the street. Hanna said, ‘What are you going to do now?’

‘That’s up to you,’ I said. ‘My work is finished. Do you still want me around for questioning?’

We arrived in the street and paused on the pavement. A motorcycle pulled up behind my car and a uniformed policeman climbed off it. Hanna glanced at him and turned to face me. ‘How do you feel about staying?’ he asked. ‘It might be dangerous – someone has already taken a shot at you.’ He held up his hand as I opened my mouth to answer. ‘I don’t mind telling you that there is pressure on me to get you off Campanilla. If it came to the crunch, I couldn’t stop you leaving if you wanted to.’

‘Do you want me to stay?’

He smiled faintly. ‘Things happen when you’re around, Mr Kemp. It would certainly strengthen my hand if you stayed.’

I said, ‘I told you yesterday I’m no pushover. People have been pushing me, wanting me to leave, and that alone makes me inclined to stay. And then there’s Ogilvie. I’d like to get to the bottom of that.’

The policeman from the motorcycle came over and gave Hanna an envelope. Hanna said, ‘I’ll let you know if there’s an answer,’ then turned back to me. ‘All right, but stay out of dark corners and let me know where you are at every minute of the day. And let’s have no secrets, shall we? Cases like this aren’t solved by inspired amateurs.’