By Ben Ando
Crime Reporter, BBC News
Police will capture richer data when testing motorists in future
The silver BMW sped down the slip road and veered across the wet, slippery motorway in front of us.
Brake lights on other vehicles lit up as drivers behind slowed down, but the BMW moved into lane three and began accelerating.
"That is terrible driving," said Alex, in the passenger seat.
"OK, going to match speed behind," replied Mike, and I felt the traffic police car surge forward as he nudged the accelerator pedal.
"Tango Delta One-Four." Alex was now on the radio. "We are following a BMW registration number... now heading north towards Medway."
Alex turned to me. "It's obvious he isn't checking his mirror at all, otherwise surely he'd have realised there was a police car right behind - even in the dark.
"This is just the kind of driving you see from someone who may have had a couple too many to drink, but still thinks they're driving safely."
I had been invited to join Kent Police's traffic officers on patrol on the first night of this year's Christmas anti-drink driving campaign.
I was sitting in the back of Tango Delta - a Volvo Estate - while Mike was driving and Alex was dealing with communications, navigation and other functions. He would also carry out any breathalyser tests.
This year, the police are using a new breathalyser device. As well as indicating the amount of alcohol in a driver's breath (measured in micrograms of alcohol per centilitre - the limit is 35) it also records the driver's age, gender, ethnicity and precise location and reading of the test.
The data will not include the driver's name or any personal information that could identify them. At the end of the patrol, data from all the tests is uploaded to a new, national database.
The annual campaign against drink-driving is underway
"Once we've got the data we can analyse it on a national scale," explains Inspector Paul Sellwood, of Kent Police's traffic department.
"Where are the drink-driving offences occurring? What are the levels? How effective is one force compared to another? What can we do to be more proactive to try to detect drink-drivers?"
The new breathalysers are being made available to all 43 forces in England and Wales.
This year, the government is spending £1.6m on advertising over the Christmas period.
"We're focusing particularly on young men because… our research shows they are especially vulnerable and likely to offend," says Transport Minister Jim Fitzpatrick.
'A bad driver'
"So we're telling them the shame, the impact on friends and family, and partners, as well as the criminal record and being treated like a criminal in a police station, is not where you want to be this Christmas."
Back on patrol, the BMW is recorded at a steady 89mph. At the next junction, Alex activates the blue lights and the car is pulled over. The woman driver immediately apologises, and explains that having just picked up her parents from the airport, she is in a hurry to get home.
She is also asked to take a breath test. Alex records the new data when prompted, then asks her to blow steadily into the tube. The test is negative - she isn't a drunk driver, just a bad one - and this time it's just a fixed penalty of £60 and three points on her licence for speeding.