Buttler displayed the world-weariness Patrick had seen before. ‘I don’t think that would be a likely order of events, Mr Duke.’

‘No,’ said Patrick flatly. ‘I can see the potential significance of that evidence. It does indeed point to a second party being present during the events that preceded the death. What I cannot see is why you have dragged Ms Shah down here to follow a line of detection which has absolutely nothing to do with her.’ He paused for emphasis. ‘And without providing an iota of credible evidence for it.’

‘Ms Shah,’ continued Buttler, ignoring him, ‘saw Sir Francis early that evening. She says she was summoned back to his office though we can find no corroboration of that. Then she became the person who found him.’ Buttler turned to Sara, adopting his most sympathetic expression. ‘I’m a simple person, Ms Shah, with what you might think is a simple mind. But in my experience it’s the simple explanation that is often right. So let me suggest one that has the advantage of chiming with the known facts. After you left the office around 7.20 p.m., you waited in the local area until Ms Yaseen departed. You returned to the office, as you and Sir Francis had arranged. You had a sexual encounter which eventually led to his accidental and unfortunate death. Understandably frightened by this, you fabricated a text with the aim of showing you only returned to the office later in the evening for work reasons. If this, in outline, is what happened, now is the time to tell me. There will be no legal consequence, no charges. You will have committed no offence. The only offence you’re in danger of committing is if you withhold evidence which would assist us in resolving the cause of death.’

Sara raised her eyes at Buttler, engaging him with ferocious intent. ‘Look at me, Mr Buttler,’ she said. ‘Who do you see?’

‘I see an attractive, intelligent young woman, Ms Shah.’

‘You’re wrong. You see someone who is committed to their work and who lives their life according to a certain set of ethical and religious rules.’

‘I can’t allow appearances to stand in the way of resolving this tragic event.’

‘You’ve a job to do. I understand the suspicions you must allow yourself to have. But you must understand that, being the person I am, your theory is wholly impossible.’ The flatness of her words was laced with a quiet fury.