Set in 1968 according to this.
Inspector George Gently: Gently Northern Soul
It's 1968 and the racial unrest sweeping the United States has reached British shores, with the National Front launching a tirade against immigration and "multiculturalists' policies".
But racial harmony can be found at the all-nighters, where disillusioned young people, black and white, escape the boredom of factory life to dance the night away to obscure soul music. In Newcastle, the haven of equality found at the Carlton all-nighter is destroyed when a young black girl Dolores Kenny (Pippa Bennett-Warner) is murdered.
Chief Inspector George Gently (Martin Shaw) soon uncovers a disturbing and malevolent racist undercurrent lurking both within the local community and his own police force.
Set against the backdrop of the assassination of Martin Luther King, Gently and Bacchus (Lee Ingleby) have their eyes opened to the shocking consequences of casual racism, as racial tension spirals out of control, leaving a path of destroyed friendships, love affairs and families in its wake.
Refusing to let deep-seated prejudices cloud their vision, Gently and Bacchus work tirelessly to unmask how Dolores died.