She laid the spoon against the rim of the tray and turned seriously to face him.

‘I’m worried about Joanna,’ she said. ‘I don’t know the others well enough to tell but I think she’s going through some sort of crisis. She was always vulnerable, a bit neurotic. Hardly surprising considering her background. She never got on with her mother and by the time I knew her the relationship had pretty well broken down. I don’t think it was Joanna’s fault. I don’t know Olivia well but she seems incapable of warmth. Joanna adored her father but of course he was hardly ever there – there was always business in Westminster and he travelled a lot. She was one of those thin, nervy children given to temper tantrums, rather spiky, always in trouble. She never got the knack of protecting herself from being hurt.’

George listened patiently. Molly tended to talk as if she were preparing a report for the juvenile court but the information was useful all the same.

‘I remember that there was something of a scandal when she was at college,’ Molly went on. ‘The story went that she took a heroin overdose. Certainly she was very ill. Olivia and Marcus hadn’t realised before that she was having problems. She was shipped off to some private clinic to get sorted out. The family claimed that she had some mysterious illness, though it was pretty clear to most people that she was an addict. It’s impossible to keep that sort of thing quiet. The Grenvilles seemed to be embarrassed by the whole affair. They never seemed to show any concern for Joanna.’

‘Do you think she might be taking drugs now?’

‘I don’t know,’ Molly said. ‘She was rather excitable this afternoon, but I think she had been drinking.’ She paused. ‘I’d thought she was much more settled recently. Not happy, exactly, but settled. She’s been married to Simon for ten years. The pottery seems to be very successful. She’s making quite a name for herself. She’s even established reasonable relationships with her mother and father. She’s still quite neurotic – always following the latest diet fad, worrying endlessly about her health – but there are lots of middle-class women with the same sort of self-obsession.’

‘So what’s the cause of the present crisis?’ George said. ‘ Do you think she can have been involved in Ursula’s death?’

‘No,’ she said. ‘I don’t think so. They were very close at one time. She used to come here a lot when she was a child. I wish I could persuade her to talk to me.’

When the meal was over George was restless. He wanted to move the investigation on but Sunday night was hardly a convenient time to make uninvited visits to Grenville and his family and it was too dark to begin his search of the hill.