Tierney has a phone call to say Alison Dunn had died the previous year. Tierney looks up her file to see that Dunn had died on 8th August 2016 so this is set in 2017. The vehicles used primarily in the show have 2014 and 2016 number plates so would indicate that this was true to the setting of the show.
The song playing in the car radio when Marcus and Shirley are driving together is Dance Hall Days by English new wave band Wang Chung.