Port, who is currently serving life behind bars, lured Anthony Walgate, 23, Gabriel Kovari, 22, Daniel Whitworth, 21, and Jack Taylor, 25, to his home in Barking between June 2014 and September 2015 after making contact with them on gay and bisexual dating apps such as Grindr. He then spiked them with lethal doses of the drug GHB, raped and killed them, and finally disposed of their bodies outside his flat or in a nearby graveyard.

The series, which airs its final episode tonight, has been widely praised by viewers for its victim-focused narrative, powerful storytelling, and chilling performance from Stephen Merchant.

Sheridan Smith, who plays bereaved mother Sarah Sak, has also been lauded for her true-to-life performance. While the series focuses on the families and loved ones of all four victims, it it undoubtedly Smith who drives the drama forward with her curiosity, rage and heart-wrenching grief as she fights to uncover the truth of what happened to her son Anthony Walgate, a fashion student from Hull, who became Port’s first victim.

Four Lives: Sheridan Smith’s emotional speech as bereaved mother Sarah Sak sums up the cost of police injustice