A condescending smile. ‘We’ll interview you formally at the custody suite. You can comment on the toxicology report then. There’s no point in having an argument in the car.’

‘I’m entitled to a solicitor. I want you to telephone John Thornton of Thornton Associates, at once.’

She doesn’t reply. The black holes that she has instead of eyes harden.

Inside the custody suite they remove my jewellery and my iPhone, and place them in brown paper evidence bags.

Photograph. Blinking in front of a computerised camera.

Fingerprints. Fingertips splayed on a machine like those I’ve seen only once before at Miami Airport.

DNA. PC Jenifer Tomlinson takes a swab by scraping my cheek with a cotton bud. She leans over me and forces me to taste her stale breath. She frogmarches me to a cell and locks me in.

The cell is worse than my worst imaginings, worse than my deepest fears. It is a hard white plastic bubble, with a shelf-like indentation in the wall for a bed. No windows. High ceiling. It looks like a hole inside a beehive made of slippery plastic. It contains a small metal toilet, with no toilet paper. That disgusts me. And a hole in the wall that sprays water. To drink. To wash my hands. So basically if I need to do a number two, I cannot wipe my bottom or wash my hands hygienically. I’m so upset and stressed that I am already trying to suppress diarrhoea. I look up. Cameras are pointing down at me. So this is the game the police play. No dignity. No privacy. I lie on the hard plastic slice in the wall and cry inside. I cannot think. I cannot sleep.

At last the window in the door of my cell is opened. PC Jenifer Tomlinson’s head appears. ‘I’m coming into the cell to take you to the interview room,’ she warns me. ‘Sit up and don’t try anything on. You are being watched.’

My solicitor, John Thornton, is waiting for me in the interview room. A room padded with plastic. Plastic table and chairs. Cameras watching. Recording. The sight of him comforts me a little. Kind eyes. Neat face. Rolls-Royce brain.

‘You can have ten minutes alone,’ Jenifer Tomlinson announces as she presses a button in the control panel. ‘I’ve turned the recording off so that you can talk in private.’ There is a pause. ‘Just ten minutes,’ she repeats as she leaves.

‘No time for small talk. I know you’ve been arrested for the murder of your mother-in-law.’ John Thornton stares at me. ‘What do you know about her death?’

‘Nothing,’ I snap. ‘They told me in the car that they think I poisoned her with arsenic. That is just ridiculous. Where on earth would I get it from?’