The parents of the murdered Labour MP Jo Cox say little progress has been made to heal toxic divisions in society since she was killed by a far-right extremist in 2016.

They were speaking at the end of a 288-mile charity bike ride in support of a charity set up by the family after her death.

Forty cyclists rode from her Batley and Spen constituency to central London over five days to symbolise her journey from her home to becoming an MP.

The ride included 1,820 metres of hill climbing on the first day, and challenges from last week’s record-breaking heatwave.

At the end of the journey, Cox’s family said divisions in society and the “toxicity” of the discourse in public life had worsened since her death.

Sister of the murdered MP Jo Cox, Kim Leadbeater (centre) joins fellow bicycle riders after arriving in Flat Iron Square in London. Photograph: Jonathan Brady/PA

Her father, Gordon Leadbeater, said: “After Jo’s murder, a lot of people spoke the right words about how it was time to heal some of the divisions in the community. Sadly I don’t think we’ve seen a lot of progress and there are one or two individuals in all areas of the spectrum who seem to be making things worse.”

Referring to a plaque in parliament in her memory, her father said he wished the individuals concerned “would turn around and look at that before they open their mouths”.

“No one disagrees with what Jo stood for – more in common, treating one another with respect.”

Cox’s father and her mother, Jean, said the charity bike ride was one way they hoped to leave a legacy for their daughter’s two young children.

Gordon said: “It would have been easy for us to sit at home and pull the curtains but that is not what Jo would have wanted.”

One of Cox’s Labour colleagues, Bermondsey and Old Southwark MP Neil Coyle, called the event “an extension of the positivity that is Jo’s legacy”.

Coyle added: “We have a really volatile national situation and I think the country is at a crossroads and is still deeply divided after the referendum.

“Anything that helps bring people together through Jo’s legacy is really important and we don’t celebrate when it happens enough. Government, in particular, doesn’t invest in that social cohesion.”