‘Detective chief inspector, we are all in a terrible state of shock, absolutely terrible. We have heard so many rumours, mostly from journalists, but nothing in detail from the police.’

‘I did try repeatedly to ring you at the office this morning,’ Gabby said defensively.

‘Yes, my PA told me. I was on my way back from Mumbai, arriving at Heathrow first thing, but I had already heard from a PC Oldroyd who answered my mother’s phone when I rang it. I’m afraid his account was a little bit more informative than what was passed on to me by your liaison officer.’

‘That was me,’ Gabby said. ‘It’s not something we want to leave as a phone message and I didn’t want to tell your PA all the details, for obvious reasons.’

He spread his arms. ‘Perhaps you can tell me now. Is it true that she was hit on the head by a cyclist with a hammer? Because I cannot believe that. She would not have got into an argument with somebody like that. She really wouldn’t.’

‘I don’t want you to jump to any conclusions about this,’ Gillard said. ‘We have several active lines of inquiry, and the passing cyclist is certainly somebody we would like to speak to. We always try to manage any details, particularly the more distressing ones. So I don’t know where you heard this story. I hope it wasn’t from the PC.’

Harry stopped to blow his nose extravagantly. ‘No, it was from a journalist.’

Gillard was impatient. How on earth do they get to find out so quickly? But he said nothing. He left it to Gabby Underwood to describe in the blandest and most neutral terms the death of Mrs Roy. Harry nodded as Gabby said that a witness had described his mother throwing a ball for her boxer dog.

‘Oh, dear Bertie. The loyalist of companions,’ Harry said. ‘He surely would have defended her to the death.’

Kiara nodded, and stroked her brother’s knee, her gloved fingers just visible beyond the sleeves. ‘What happened to Bertie?’

‘He’s being looked after by one of our dog handlers. We needed to do a DNA test in case he bit the assailant, and get him checked over by a vet, but I think he can be returned to you shortly.’

‘Could you put him in an identity line-up?’ Harry said. ‘He presumably saw the attacker, and would bark at him?’

Gillard suppressed the urge to laugh. ‘I’m sure it would appear plausible in a TV show, but in fact it wouldn’t be the kind of evidence that a court would accept. The Crown Prosecution Service would be horrified if I even suggested it. But if Bertie did bite the attacker, and we can find a piece of clothing or scrap material with both their DNA on, we could be in business.’

Harry excused himself, and Gillard could hear him out in the corridor, his plaintive voice getting a reassuring answer from some unseen woman. It was almost six, and Kiara suggested that they watch the BBC TV news together. Gillard agreed, checked his watch, and saw he had time to do what he needed before it began. He asked her the way to the bathroom. The room, just a few yards along the passage to the left, was opulent, high-ceilinged and contained several mirrors. Gillard took a tissue from his pocket, moistened it under a gilt tap, and carefully wiped the top of the cistern and the vanity unit. He then slipped the tissue into a Ziploc bag in his pocket and sealed it. He flushed the toilet, washed his hands, then returned to the lounge.