John McDonnell opened his response to Philip Hammond’s first Autumn Statement with a tribute to Jo Cox.

The shadow Chancellor said Ms Cox’s killing was “an attack on democracy itself” after right-wing extremist Thomas Mair was found guilty of her murder.

“This morning we’ve heard the verdict from the trial following the tragic murder of Jo Cox,” Mr McDonnell told the House of Commons.

“Jo Cox’s murder robbed this house of a fierce advocate for social justice and a passionate campaigner.

“Her killing was an attack on democracy itself. Our thoughts are with her family this morning.”

Mair was convicted of murdering the 41-year-old Remain campaigner and mother-of-two outside her West Yorkshire constituency surgery in the run-up to the EU referendum.

Mair was jailed for a whole-life sentence for what the MP’s widower, Brendan Cox, branded “a political act and an act of terrorism”.

Jo Cox tributes - in pictures Show all 20 1 /20 Jo Cox tributes - in pictures Jo Cox tributes - in pictures Floral tributes and candles are placed by a picture of slain Labour MP Jo Cox at a vigil in Parliament square in London AFP Jo Cox tributes - in pictures Tributes to Labour Party MP Jo Cox are placed on her houseboat in Wapping in London REUTERS Jo Cox tributes - in pictures The Union flag at half-mast on top of Portcullis House in London after Labour MP Jo Cox was shot and stabbed to death PA Jo Cox tributes - in pictures Labour leader Jeremy Corbyn (2R) and deputy leader Tom Watson (L) light candles as they attend a vigil to slain Labour MP Jo Cox in Parliament square in London AFP/Getty Images Jo Cox tributes - in pictures Labour Party leader Jeremy Corbyn and deputy leader Tom Watson (rear) arrive to leave tributes at Parliament Square PA Jo Cox tributes - in pictures People leave St Peter's Church after a vigil in memory of Jo Cox REUTERS Jo Cox tributes - in pictures Flowers left at Parliament Square opposite the Palace of Westminste, following the death of Labour MP Jo Cox PA Jo Cox tributes - in pictures People react as they look at tributes left for Labour Member of Parliament Jo Cox in Parliament Square, London REUTERS Jo Cox tributes - in pictures A man writes a message at Parliament Square PA Jo Cox tributes - in pictures People stop to look at tributes left at Parliament Square opposite the Palace of Westminster PA Jo Cox tributes - in pictures A woman arrives to lay flowers at a statue to Joseph Priestly in Birstall near to the scene where Labour MP Jo Cox was shot AFP/Getty Images Jo Cox tributes - in pictures Tributes at Parliament Square opposite the Palace of Westminster PA Jo Cox tributes - in pictures A woman places candles in tribute to Labour Party MP Jo Cox REUTERS Jo Cox tributes - in pictures A member of the public signs a memorial for British MP Jo Cox in Parliament Square, London EPA Jo Cox tributes - in pictures People sign messages of condolence for MP Jo Cox during a vigil in Parliament Square in London Getty Images Jo Cox tributes - in pictures Flags at half mast outside Scottish Parliament in Edinburgh, after Labour MP Jo Cox was shot and stabbed to death in the street outside her constituency advice surgery in Birstall PA Jo Cox tributes - in pictures People arrive in Market Square with floral tributes after the death of Jo Co Getty Images Jo Cox tributes - in pictures Floral tributes are placed in Market Square next to the statue of Joseph Priestley following the death of Jo Cox Getty Images Jo Cox tributes - in pictures Floral tributes are brought to the scene after the death of Jo Cox Getty Images Jo Cox tributes - in pictures A police officer carries bunches of flowers at the scene of the shooting of Labour MP Jo Cox in Birstall REUTERS

Jeremy Corbyn also called Ms Cox’s murder “an attack on democracy” and said it had “robbed the world of an ambassador of kindness and compassion”.

Following her murder, Mr Corbyn said that British society had lost “one of our very best”.

Speaking after the guilty verdicts were announced, he said: “Jo Cox believed passionately that all people can achieve their full potential given the opportunity.”

“Jo’s values were lived out in her last moments, when she bravely put the safety of her staff before her own,” he said.

“Jo is someone the Labour Party will forever be extremely proud of.”

“The single biggest tribute we can pay to Jo and her life will be to confront those who wish to promote the hatred and division that led to her murder.”

Mr Corbyn called Ms Cox a “loving mother and wife” and said he hoped the verdict had “delivered some sense of justice to those grieving, particularly Jo’s family, who all of our thoughts are with at this time”.

Sue Hemming, head of the Special Crime and Counter Terrorism Division at the Crown Prosecution Service, said: “On 16 June, Thomas Mair carried out the brutal murder of Jo Cox – a defenceless mother of two young children who served her constituents with passion, exuberance and vitality and was proud to represent a diverse community.

“Several people courageously intervened to try and save Ms Cox, including 77-year-old Bernard Kenny who was stabbed by Mair and sustained serious injuries as a result.

“Mair has offered no explanation for his actions but the prosecution was able to demonstrate that, motivated by hate, his pre-meditated crimes were nothing less than acts of terrorism designed to advance his twisted ideology.”