This morning, as we mourn the untimely and shocking death of Labour MP Jo Cox, we cannot know exactly what motivated the brutal attack on her as she went about her job, serving her constituents and her country.

But what we can reflect upon is the potential vulnerability of politicians and campaigners and the changing mood in British politics – a change for the worse that has shocked and frightened me in recent weeks.

Only 1 per cent of people are members of a political party and the number who go on to hold public office is far lower. Being active in politics is a brave, responsible and selfless thing to do, whichever side of the fence you are on. There is a huge shortage of candidates willing to put themselves forward, to go through public grillings and to being held personally accountable for decisions that affect hundreds or thousands of people.

Being involved in politics, from campaigning in your community to standing as a councillor or MP, is putting yourself out there. Sadly, that means making yourself vulnerable too. But it is a right and a responsibility that makes our democracy what it is – something I will always defend.

Birstall Reverend on Jo Cox

As a campaigner for Britain Stronger in Europe, and as a former councillor, I have noted how public debate has deteriorated in recent weeks and years; how respect for public office has waned; and – an insight that feels disturbingly prescient this morning – how much more vulnerable those who choose to engage in politics have become.

For the last few weekends, I have been campaigning at the Stronger In stalls hosted by towns around the south west of England. The language directed at our youngest campaigners, many of them female, has been threatening and violent. It frightened me – and I’ve been active in politics for a decade, stood for election, and been elected.

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

Yes, I’ve had some scary constituents I worried about having access to my address and telephone number. But now, after the death of Jo Cox, and as a young woman who campaigns day in and day out, I fear for our politics.

Six weeks ago, when I was volunteering, a man compared the EU to Hitler. I was shocked. “How ridiculous,” I thought. Then last weekend we were called traitors and threatened with execution by passers-by.

After hearing of yesterday’s tragedy, I mentioned to a man in the bus queue some of the language campaigners had been subjected to and how vulnerable they had felt. He response was, “Well don’t volunteer then”. None of us volunteer to be violently abused; we do so because we are motivated to help others. I’m sick of people saying, “gosh, you must have thick skin”. That’s not the way it should work.

This change of attitudes worries me greatly and has consequences, not least for social cohesion. We must all be measured and reasoned in our arguments or unreason will rule.