Labour MP Jo Cox was murdered outside a constituency surgery in Birstall. Thomas Mair was unanimously convicted of murder and related offences, and the sentencing judge imposed a whole-life order after finding the crime exceptionally serious and ideologically motivated.

On June 16, 2016, Jo Cox, the Member of Parliament for Batley and Spen, arrived in Birstall for a constituency surgery. She was attacked in the street and died from her injuries. A passer-by, Bernard Carter-Kenny, was seriously wounded when he tried to help her.
Cox was 41 and had entered Parliament in 2015. The criminal trial concerned one defendant, Thomas Mair. The prosecution did not need to establish a political motive in order to prove murder, but the evidentiary record and the sentencing decision addressed the ideological character of the attack.
Mair was arrested shortly after the attack. Witnesses, CCTV and physical evidence formed part of the prosecution case. He offered no substantive defence at trial; because he did not enter pleas himself, not-guilty pleas were recorded on his behalf as required by law.
On November 23, 2016, an Old Bailey jury unanimously convicted Mair of murdering Jo Cox. He was also convicted of causing grievous bodily harm with intent to Bernard Carter-Kenny, possession of a firearm with intent to commit an indictable offence and possession of an offensive weapon.
At sentencing, Mr Justice Wilkie concluded that the murder was committed to advance a political, racial and ideological cause associated with violent white supremacism. That finding matters editorially: it is grounded in the court's sentencing record rather than inferred from political debate surrounding the 2016 referendum.
The judge imposed a whole-life order for the murder. The separate sentence for the serious assault on Bernard Carter-Kenny was 20 years, with additional concurrent sentences on the weapons offences. A whole-life order means there is no ordinary minimum term after which parole can be considered; release, if ever, would depend on exceptional executive clemency.
Jo Cox is attacked as she arrives for a constituency surgery; Bernard Carter-Kenny is wounded while intervening.
Thomas Mair is prosecuted for murder and related offences.
An Old Bailey jury unanimously convicts Mair on all four counts.
The sentencing judge imposes a whole-life sentence for the murder and concurrent sentences for the other offences.
The criminal responsibility for Jo Cox's murder is Solved / Adjudicated. Thomas Mair remains subject to a whole-life order. This page does not equate broader political disagreement with criminal responsibility and does not reproduce extremist material associated with the offender.
The trial established Mair's guilt for murder. The sentencing judge also found the crime ideologically motivated. Those judicial findings are distinct from speculation about wider political causes or collective blame, which this page does not adopt.
Last reviewed: August 27, 2026