The ornate black gates that loom at the mouth of Downing Street were designed to look as though they have guarded the entrance for centuries. In truth, their installation was a relatively recent event in the history of Britain’s most famous street. They were put in, as a protection against terrorism, over the Christmas period in 1989 when Margaret Thatcher lived there. In a more innocent age, anyone could wander up Downing Street as they pleased and even have themselves photographed in front of the polished letter box of Number 10, posing there as if they were prime minister. The gates put a definitive end to that. While commissioned to enhance her safety, the barrier turned out to be damaging for Mrs Thatcher. Opponents seized on the erection of the gates as symbolic of how imperiously remote she had become towards the end of a premiership that would be terminated less than a year later. When Tony Blair moved into Number 10 in 1997, he considered having the gates removed to signal the arrival of a fresh and open kind of government before being persuaded that they had to be retained to keep the street safe. With the passage of time, he would also be accused of being another arrogantly detached prime minister gated off from the public. The concrete and steel shield that now encases parliament was also a response to terrorist threats. The accretion of security has made our centres of power somewhat safer from violent attack, but at the price of making politicians seem more distant from the public. When people bemoan “the Westminster bubble”, that complaint is fuelled by the sense that SW1 is physically cut off from the rest of the country. There’s a tension between politicians being accessible to voters and the protection of elected representatives, their families and staff from those who mean them harm. The conundrum has been made tragically sharper by the killing of Sir David Amess. The response to his death from parliamentarians has come in two parts. The first was an outpouring of sorrowful affection for an unusually well-liked and effective backbencher with a yard-wide grin and a flamboyant zest for life. When the Commons paid its tributes, one colleague recalled Sir David celebrating his knighthood by dressing up in medieval battle finery, mounting a horse and riding around his constituency. Others noted his indefatigable campaigning to secure city status for Southend, a wish posthumously granted. The other response has been a torrent of accounts, from MPs of all parties, about being inundated with harrowing abuse, including numerous rape threats and death threats, and the strain this puts on them, their families and aides. It is clear – and this is bad – that a lot of MPs feel unsafe doing their job. It is also clear – and this is tremendously bad – that many feel especially vulnerable in their constituencies. Kim Leadbeater, the MP for the Batley and Spen seat once represented by her sister, Jo Cox, who was murdered by a neo-Nazi outside her constituency surgery, revealed that her partner has asked her to step down from parliament. Sir David died while holding a surgery in a church. Two is dreadful. Four is a pattern. In 2010, the Labour MP Stephens Timms suffered a life-threatening stabbing by an Islamist extremist while holding meetings with constituents in east London. In 2000, Andrew Pennington, an aide to the Lib Dem MP Nigel Jones, was killed as he tried to shield the parliamentarian from an assailant wielding a sword. Some propose that encounters between MPs and constituents become much more formal or move online, but many are highly resistant to that. It is hard for politicians to urge GPs to see more people face to face or exhort the police to be more visible on the streets if they stop doing these things themselves. Many MPs share Sir David’s view that constituency surgeries are a fundamental component of their role, a precious opportunity to be able to talk directly to voters about their problems and concerns. A small minority might hanker for the bad old days when many constituencies were lucky if their MP deigned to visit once every three months. The great majority of parliamentarians think that barricading themselves off from their voters would be hugely undesirable, magnify the often unjust accusation that they are “out of touch” and deepen the mistrust many of the public have for politicians. It has been less often said, but it is also true, that many parliamentarians think being deemed “a good constituency MP” helps build a “personal vote” and improve re-election chances. After four grave attacks on parliamentarians this century, three leading to a fatality, it is promised that safeguarding will be improved. The Speaker, Sir Lindsay Hoyle, and the home secretary, Priti Patel, have declared that all MPs will be offered trained security protection when meeting constituents. That may help, but short of placing MPs inside impenetrable fortresses their safety can never be absolutely guaranteed. This comes with a price. The talent pool of politicians will shrink when able and decent people who might have made a valuable contribution to national life see MPs living in fear and make a different career choice rather than expose themselves and loved ones to atrocious abuse and risk to life. Another harm to democracy is that scared MPs may avoid contentious topics or self-censor their opinions for fear of the consequences of attracting the wrong kind of attention from extremists. Then there is the complex of questions about how much of a connection can be made between the death of Sir David and the general toxicity of political culture. Some argue that doing better at safeguarding MPs from physical attack should be accompanied by an effort to elevate public respect for their profession. I agree that it is a crude and destructive caricature to depict all politicians as mendacious graspers. There are highly public-spirited people in parliament and there are absolute shits. Most MPs are at neither end of the spectrum, but somewhere along it. Part of the problem is that the expenses scandal left an enduring taint on the public’s view of parliament. The reputation of politicians isn’t helped when some continue to behave in ways that give force to the charge that they are self-serving frauds. Remedying that lies mainly in their own hands. Others make a link between physical threats to MPs and a coarsening of political discourse. Britain has a long and vital tradition of spirited debate and its democracy is the more vibrant for the fiery testing of political ideas and the robust scrutiny of the characters of politicians. The price we pay is that this can cross a line into something uglier. This is not new. During the 1945 election campaign, Winston Churchill made the outrageously untrue claim that a Labour government would introduce “a political police… some form of Gestapo”. A few years later, one of Labour’s great men, Nye Bevan, described the Tories as “lower than vermin”. The use of that kind of language was rarer in the 1940s and those remarks were turned against both men. Incendiary rhetoric is now much more routine and the most hideous bile can be spewed on social media where trolls exploit anonymity to spread their poison. There is as yet no proved correlation between online abuse and Sir David’s death. It has nevertheless reinforced the consensus at Westminster that social media has made a significantly baleful contribution to feeding hyper-polarisation and the radicalisation that can draw some people down terribly dark paths. There is escalating pressure for the tech giants to be held responsible for the toxins they pump into the bloodstream of the body politic. Threats of violence, whether directed at politicians or anyone else, ought to be energetically dealt with by the police and the prosecuting authorities. The tone of politics is also set by politicians. There’s a danger in language – “scum”, “traitor” – which dehumanises opponents. Some of the responsibility for the debasement of the public square lies in their own hands or, rather, with how they use their own tongues. Argument can be vigorous, even vehement, without descending into the venomous. The hardest question, one that politicians have been grappling with over the decades since the installation of the Downing Street gates, is how they reconcile the tension between security and openness. Can we keep alive direct and unfiltered engagement between MPs and voters without risking further deaths? There is, I fear, no perfect answer to that. Andrew Rawnsley is Chief Political Commentator of the Observer