A low concrete roof, ugly grey curves and brown-tinted windows underneath. A hedge blocks the worst of it, but it’s clear the local planning department were having an off day when that design was approved. She drives past it and parks in one of the bays marked SCIU. In the distance she can see the distinctive yellow fluorescent vans, and climbs out of her car, walking away from the seventies monstrosity towards an altogether more beautiful building.

The Serious Collision Investigation Unit is located in the manor house next door. Ivy climbs up one side of the curved bay window, a large pillared doorway in the middle. A man waits on the steps, dressed in the usual distinctive black uniform, and holds out his hand. His muscular arms are covered with two full sleeves of tattoos – skulls, roses, thorns – his head completely shaved. His nose is wonky from previous breaks and he has one cauliflower ear. But despite his intimidating appearance, his smile is wide. Freya warms to him instantly.

‘Kevin Burton,’ he says, towering above her. ‘You must be DC West. Come inside.’

The hallway is large and grand but has clearly seen better days. The carpet is stained and threadbare, the paint chipped and peeling. A large metal shelving unit has been set up on one side, containing rows of identical black kitbags and fluorescent vests.

‘Supposed to be here temporarily, that was two years ago,’ he says. ‘Want a cuppa?’

‘Please.’

‘How do you take it?’

Freya follows him down the low-ceilinged corridors, watching him duck to get through the doorways. Temporary green fire exit signs have been put up, at odds with the period features that Freya knows must have been part of the of the original decor. He makes them both tea, handing her one in a pale blue mug with Keep Calm and Know Your Rights written on the side. Some union thing, she assumes.

He leads her into the main office. Square functional desks and computers line one side, contrasting with the round bay window behind them. One of the sash windows is open, propped up with a box file, a cool breeze blowing through. Burton pulls out a chair and she sits down next to him.

‘So, what do you want to know? It was the Stevens accident, right?’

‘Yeah. November 2018.’

‘Got it here.’ He points to the pile of brown boxes by his side. ‘Where do you want to start?’

‘Tell me everything you know.’

Burton sits back in his seat, clearly relishing the distraction from his normal work. Because of his height, the computer is propped up on two reams of paper, his chair set to the highest setting. It makes Freya feel tiny: a primary school kid listening to her teacher. But she doesn’t mind, she’s there to learn.