‘Right, let’s keep this brief,’ Gillard said, pointing to an ordnance survey map that he had taped to a whiteboard. ‘What we know so far is that businesswoman Mrs Tanvi Roy, fifty-seven, was walking her dog on Ashtead Common at around 7.20 a.m. when witnesses heard a scream. The first arrived at the crime scene within three minutes, and could see from the severity of head injuries that the victim was dead. We have been very lucky on this because that first witness was, as you will have heard, Ms Kirsty Mockett, a trainee crime scene investigator. You have her statement in front of you. In the first five minutes and with the snow already melting she managed to secure the scene, keep bystanders and their dogs away, and preserve an impression of a potentially significant cycle tyre imprint and accompanying footprint.’

‘That’s well impressive,’ said Colin Hodges, tucking into a sandwich from a paper plate stacked high beside him. Hodges and his fellow DC Carl Hoskins were almost identical mid-thirties, overweight, working-class detectives, with metal-framed spectacles and close-shaven heads. Known as Tweedledum and Tweedledee, the only easy way to tell the difference between them was Hodges’ newly-grown beard which, to his horror, turned out ginger. ‘I hope she’s coming to work for us,’ he said.

‘She is, starting tomorrow,’ Gillard said.

Claire Mulholland stuck up her hand. ‘Is the cyclist formally a suspect?’

‘Informally, yes. But I think at this stage we should stick to the formula that he is somebody we are anxious to trace. I’ll say more about this when we cover the PR angle because it’s potentially going to be a big story.’ He looked at Christina McCafferty, whose emphatically nodding head signalled agreement.

Claire made some notes, while Gillard continued. ‘I was able to get there by 7.40 a.m. When uniforms arrived five minutes later we were able to try to follow the cycle tracks before the snow melted. We can look at the tyre track images later.’ He turned to the map. ‘We traced the line of tyre marks along a public footpath which exited onto the A243 here,’ he said tapping the map. ‘This is where the track was lost.’

‘She didn’t get much of a description of the cyclist,’ Claire said. ‘Do we have anything from other witnesses?’

‘Not much. Mr Douglas Boyle, a dog walker and the second witness on the scene, said he saw a cyclist in the distance a couple of minutes before he heard the scream. All he could say was the rider was heading down the bridleway from the direction of Ashtead railway station towards the place where Mrs Roy was found. We have a good description from Ms Mockett of the three vehicles parked at the start of bridleway thirty-three, here, which is the junction of Woodfield Lane and Woodfield Road. We are currently tracing owners. She didn’t recall any of the vehicles having a cycle rack. Although it is possible to store a bicycle in a large car, I think we should probably assume for now that our cyclist arrived and left the area on two wheels.’