It is mentioned by Chief Superintendent Raymond Mallick that Wallis was married with two children.
Wallis, along with his colleague PC Vincent Butler, is one of the night shift officers on duty in 4th Street Station when an urgent call is received from DS Jayne Akers. After getting DCC Mike Dryden to sign off on the extraction, DI Lindsay Denton orders him and Butler to accompany her to the location.
Once they arrive at St. James Close to extract Tommy Hunter, Butler takes the wheel of Akers vehicle, with Wallis in the passenger seat and Akers and Hunter in the back. En route back to the station, DI Lindsay Denton leads them down a isolated country lane where the car is rammed head on by a Range Rover. The impact causes the airbags to deploy, stunning both Butler and Wallis. Before they can react, two masked gunmen (later revealed to be corrupt officers DC Jeremy Cole and DS Manish Prasad) emerge from the car and gun them down with a Mini Uzi submachine gun and Glock 17 pistol.