Beside her, O’Grady listened with acute interest. His time with the case files hadn’t been long enough for him to get to that bit yet, and he began to feel hopeful that they might just tie up this case in record time. His old training sergeant had always said that there were only ever two real motives for murder – sex and money. And here was a financial motive, right enough, staring them in the face.

‘What? No, he was paying me back. I told you that,’ Geoffrey said. ‘Don’t you remember?’

‘Yes, I remember what you told me, sir, but that might not have been the case. Perhaps he refused to pay you? Or, if he had indeed begun to do so, did you trust him to pay it all back?’ Trudy put to him. ‘After all, if he’d betrayed you once, he could do it again. Maybe you found out that he was planning to steal more money – or perhaps get an accomplice to steal the cars themselves. He could put you out of business and disappear overnight with the proceeds, couldn’t he?’

‘No, no, it wasn’t like that.’ Geoffrey, his voice rising higher in pitch as he panicked, looked from one to the other of them helplessly. ‘We’d sorted it all out. I told you!’

‘We can quite see if you decided enough was enough, sir,’ Trudy carried on, as if he hadn’t spoken. ‘By your own admission, you knew Mr Parker was going to that New Year’s Eve party. The weather was atrocious, and you knew his habit of taking one of the heavier, older cars when the weather was that bad. It wouldn’t have been hard for you to suggest that he take the Riley. Perhaps you tampered with the brakes, only wanting to frighten him, not thinking—’

‘No! I tell you, I didn’t touch the car!’ Geoffrey almost leapt to his feet in his anxiety to be believed, but a sudden threatening movement by the big-boned sergeant made him slump back helplessly into his chair once again. ‘I’m not a mechanic,’ the older man said, trying a different tack. ‘I only sell cars, I don’t know anything about the actual workings of the things! We have a mechanic at the shop to do all that! I wouldn’t have a clue what you’d have to do to a car to make it crash!’

‘Then what was so important about the car that you needed to break into a police impound yard and search it, sir?’ Trudy asked reasonably. ‘If it wasn’t to cover your tracks, what was it?’