My mental image of the inside of police stations came from watching television dramas. Old-fashioned ones, mostly, full of dingy corridors leading to dark offices with shields mounted on the walls and heavy wooden desks with swivel chairs. And in some bright communal area, a large incident board, pinned with photographs of suspects, linked by pins and string and dotted with yellow sticky notes.

Our local police station wasn’t like that. I’d walked past it a thousand times and never really noticed it until now. A 1980s multi-storey office building with tall glass doors, all chrome and concrete. The young man on the ground floor reception desk looked dubiously at the business card.

‘Is she expecting you?’

I stood my ground. ‘She told me to get in touch. Is she in?’

He narrowed his eyes, then hit a button on the phone box. His headset bobbed round his cheek.

He lowered his voice as he spoke into it. ‘There’s a Jennifer Walker, ma’am. Yes, ma’am. Right away.’

The police officer stood there in the lift lobby, waiting, as I emerged on the fourth floor.

‘Mrs Walker. How’s Gracie?’

‘Fully recovered. Thank goodness.’ I laughed nervously.

Her handshake was hard and her pace brisk as she led me past broad windows that showed an open-plan office beyond, two banks of desks crammed with people. It looked as soulless as a call centre.

She ushered me into a small, bare room with a plastic-topped table and four metal-framed chairs and gestured to me to sit. The walls were beige and the only object on them was a metallic clock with black numerals. Five past eleven.

She pulled a second chair up to mine and sat, her feet flat on the ground and her legs apart. She was no taller than me but her brusque manner and her uniform made her thick-set and masculine and, although she made an attempt at a smile, the overall effect was intimidating.

‘So, how can I help you?’

The window behind her faced down the high street. Everything looked different from this angle. The three-storey rows of shops were low and poky. The red roof of a double-decker bus slid to a halt as the lights directly below changed to red and the small figures of pedestrians, two mothers pushing buggies, a stout middle-aged man, a willowy youth, an old lady walking with a stick, pressed forward from the edge of pavement. It was the ragtag, anonymous public of which I was part, which she was here to protect.

‘It’s about the accident.’ I hesitated, feeling my way. ‘I’ve got new information. I thought you ought to know.’

‘OK.’ She nodded, her expression non-committal. ‘What’s the information?’

I took out Ella’s mobile phone and handed it to her. She looked it over, then raised her eyes, waited for me to say more.

‘It’s hers. See? Ella’s.’

I couldn’t tell what she was thinking, but it was clear she didn’t understand how significant this was. ‘It’s Ms Hicks’s phone? Had she lost it?’

‘Yes,’ I stuttered. She made me nervous. ‘I mean, she probably didn’t tell you, did she? That she’d lost it?’

She shook her head. ‘No, I don’t believe she did. Should she have?’ She seemed at a loss. ‘Was it stolen?’

‘No!’ My words were thick with emotion as I struggled to make her understand. ‘It was at the scene of the accident.’

She gave a slight sigh. ‘I’m sorry, Mrs Walker. I’m not sure I understand.’

I leaned forward, earnest. ‘It’s evidence. Of what happened. I just thought, if there’s an investigation, you might need it. It’s evidence against Ella.’

My voice sounded thin and insubstantial in the echoing acoustic of the small room.

Her eyes never left my face. ‘Evidence of what, exactly?’

‘Of what really happened.’ I sat forward, my voice rising with my frustration. ‘It was left at the scene of the accident. A woman picked it up. She saw everything and she gave it to me.’

‘Why didn’t she bring it to us, if she thought it was evidence?’

‘I don’t know.’ I looked down at my hands, clasped in my lap. ‘I don’t think she realised how important it is. It shows, you see, that Ella was on the phone at the time of the crash. The call’s logged.’ I pointed to the phone, willing her to take me seriously and to look for herself. ‘That proves it.’

She didn’t even blink. ‘Proves what?’

‘That she was responsible too. For the accident. Yes, OK, that poor young woman veered across the road. But why didn’t Ella react? Swerve to avoid her? Because she was on the phone. She was preoccupied. That’s dangerous driving, right there.’

Below, in the street, the lights changed a second time and the traffic slowed, stopped. A ragged line of pedestrians hurried across.

‘Is that why you’ve come to see me?’

‘Ella was shouting at someone. Angry. Telling them to leave her alone. Clearly she wasn’t watching the road properly. The accident – that girl’s death – Ella is to blame too.’

She didn’t answer. She just waited.

‘That woman heard her. She’s a witness. And so did Gracie, my daughter. She was right there. She saw everything.’

She got to her feet. ‘I’m afraid I’ve got a lot of work to do.’

I jumped up. ‘But you need to do something. If she was distracted—’

The police officer raised a hand to silence me. ‘These are very serious allegations. You should be careful.’

‘Me?’ I blew out my cheeks. ‘She’s the one who—’

‘Mrs Walker. The coroner has already given a verdict. Accidental death. The case is closed.’ She handed the phone back to me. ‘You might want to return this to Ms Hicks as soon as possible, if it’s her property.’

I shook my head. ‘But two people heard—’

‘Listen. Firstly, even if this were a continuing investigation – which it is not – testimony from a traumatised three-year-old would not be reliable. Secondly, even if the timing of the call had matched the exact time of the accident, no coroner would have found Ms Hicks responsible.’ She leaned in closer to me. ‘The post-mortem found that Ms Parkes had excessive levels of alcohol in her blood at the time of the collision. She had a history of similar offences.’

I stared at her, my cheeks hot. ‘So you’re not going to do anything?’

Her face was hard. ‘Such as?’

‘I don’t know. You’re the police officer, not me. Prosecute her for dangerous driving. If Ella hadn’t been distracted that young woman might still be alive today. Think of her family.’

She turned away from me towards the window and her shoulders rose and fell as she breathed deeply. I waited, my legs juddering. When she turned back to me, her features were stony.

‘Mrs Walker, I understand you’ve been through a lot.’

‘She had my daughter in the back. She nearly died too. What if I’d lost her? Then what?’

‘That’s enough, Mrs Walker.’ Her tone was icy.

‘She wasn’t watching the road. She was on the phone, shouting. How’s it not her fault, at least—’

The police officer raised her hand and the look on her face silenced me. She shook her head, crossed the room and opened the door for me to leave.

At the lift, she said: ‘I’m very sorry. But as far as the police are concerned, this is now over. Take my advice. Leave Ms Hicks alone. Leave everyone alone. You have a lovely daughter. Go home and look after her.’

The lift doors opened and I stepped inside. She reached in to press the button for the ground floor. By the time the doors slid shut, she had already turned back towards the soulless office.

Downstairs, I walked straight out into the street and stood at the crossing, waiting for the lights to change, wondering which unseen people might be watching me from above and trying hard not to cry.