For ITV's Tonight programme, Jo Cox's sister Kim Leadbeater explores whether Britain has become angrier and more intolerant since the MP was murdered three years ago. Here, she writes about what she found during the course of making the programme.

It’s hard to believe it’s three years since my sister was murdered.

Jo had only been an MP for just over a year, and we were so proud of the work she had started, making a difference in our local area and showing what an excellent addition she was to Westminster. On 16 June 2016 she was killed in a politically motivated attack.

Jo was a fantastic sister and a passionate humanitarian, who went into politics to help people and make a difference on important issues such as loneliness and social isolation and protecting civilians in areas of conflict.

Jo Cox was murdered three years ago. Credit: Kim Leadbeater

I can’t think about the day Jo was killed. I imagine that at some point I will have to, but I know I’m not ready yet. Instead, I am working hard as an Ambassador for The Jo Cox Foundation to create a powerful legacy for my sister on projects to bring communities together and facilitate a more positive public debate.

Our biggest campaign is the ‘Great Get Together’. Held every year on Jo’s birthday – the 22nd June - it’s a national initiative which provides a platform for people and communities to connect through all kinds of events, such as picnics, street parties and sports days.

Supported by an amazing network of people, I am keen to make a positive difference, and I believe we all have a part to play in creating a strong, compassionate country.

There was a short period after Jo was killed when everyone said the right things: we need to have a calmer, kinder politics; we need to treat each other well and behave in a civil manner.

But after the referendum, and in the last three years, it feels like all that has been forgotten. The way we talk to each other seems so vicious and toxic.

Brexiters are called fascists, Remainers are called traitors, and those who disagree with us are ‘the enemy’. The language has become increasingly violent and there is a tangible sense that many people are very angry.

Kim Leadbeater has been working as an ambassador for The Jo Cox Foundation since her sister's death to help bring communities together. Credit: ITV Tonight

I’m proud to live in a country where we can express our opinions freely - it is a cornerstone of our democracy - and it would be unrealistic to think that we can all agree on everything all of the time.

Indeed, my sister Jo was a firm believer in robust debate and discussion. But what we have seen recently seems to have gone beyond this – personal insults and vicious verbal abuse seem to have become the norm, and this has at times led to violence and physical attacks.

We seem to spend a great deal of time shouting at each other rather than listening and trying to understand each other’s point of view.And, without wishing to be accused of scaremongering, I’m worried that unless we do something about this soon, it could get even worse. And I would hate for any other family to have to go through what we have been through, and continue to go through, every day.

Kim spoke to MPs about the abusive messages they have received. Credit: ITV Tonight

In tonight’s documentary, I try to find out whether things are actually getting worse and if so, what we can do about it. What I found shocked me.

I return to where Jo worked, parliament, to meet three MPs who have received varying degrees of abuse, often because of their stances on Brexit, but on other issues too. They tell me how they’ve received personal insults, sexually abusive messages, and even death threats.

With the University of Sheffield, we analysed the tweets sent to MPs in the month of May. We found that more than 40,000 responses were abusive. Remarkably, that’s almost four times higher than the same period last year.

Whilst we were doing our analysis, the EU elections were happening and there are year-on-year more people using Twitter, which might go some way to explain the jump. But it’s still a lot for MPs, their staff and families to deal with. We may not be surprised to see that Brexit sparked some of the greatest levels of abuse.

But the MPs tell me this toxicity isn’t limited to them. They say police officers, ambulance drivers, councillors and teachers are seeing higher levels of verbal and physical abuse.

Countdown presenter Rachel Riley has also received anti-Semitic comments online. Credit: ITV Tonight

Celebrities, too. I meet Countdown presenter and Strictly star Rachel Riley who describes some of the nasty anti-Semitic comments she receives. She tells me how it can damage your mental health, particularly when she receives messages of Holocaust denial, something that deeply affects her.

What I perhaps found most shocking making tonight’s programme, is that those who don’t choose to be in public life are receiving abuse too.

Allan Bryant’s son, who’s also called Allan, went missing five years ago. The family have understandably been trying to keep his name in the papers and on social media to find out what happened to him, but have had torrents of abuse. People saying “get over it, he’s dead” or “just admit it, you killed him”. Some have even made up claims to have killed him – all, it would seem, just to hurt the family.

Allan Bryant's missing son has also received hurtful online abuse. Credit: ITV Tonight

Whilst I believe that social media can be used for lots of positive things, the perceived anonymity of the internet also seems to have given people the freedom to treat people despicably. What has gone wrong in our society?

The statistics show things are getting worse: we sent Freedom of Information requests to all police forces in England and Wales. 25 responded and from them, we found the number of people charged for malicious messages since the year Jo was killed has risen by 38%, and the number of ‘threats to kill’ reported to the police has gone up 70%. In such a short space of time, I find that extremely worrying.

I wish I had the answers as to why this growing anger is happening. I suspect, as with most things, there isn’t one specific reason. People I’ve spoken to say it could be because our busy lives and ‘on demand’ culture has made us more impatient, or perhaps a polarising referendum has seeped into our wider lives. Maybe the internet has made people feel empowered to say things they previously wouldn’t.

Certainly the web has played a role in connecting those with similar, often extremist, views.

Kim met with reformed far-right extremist Ivan Humble. Credit: ITV Tonight

I meet Ivan Humble, a reformed far-right extremist who was recruited into the English Defence League through social media.

But he told me that the foundations were already there, and the EDL simply provided a convenient answer. The concerns he had were the lack of jobs and mental health services in his local area, and Islamist hate preachers online. He felt if someone had listened to his concerns and addressed them, he might not have been drawn to extremism for answers.

He is repentant and keeps his EDL tattoo as a symbol of who he once was, but on the other arm he has Jo’s now-famous words “We have more in common than that which divides us”.

And I think they are words we all need to remember. We don’t always have to agree, we don’t even have to like each other, but I believe that every one of us, whether we’re a politician, a celebrity or a member of the public, should think about the things we share and have in common as human beings.

We all have to manage our busy lives, pay our bills, feed our children and find a way to live together in peace. But we can only do this by trying to understand each other, listening to each other’s views and opinions and thinking about the way we speak to each other.

Only that way can we try and bring our country together.

‘Angry Britain: Beyond Repair? – Tonight’ airs on Thursday at 7:30pm on ITV