Since the turn of the century, attacks on MPs have taken place with alarming regularity.

       The attack on Sir David Amess on Friday, in which he was stabbed to death at a constituency surgery, will once again prompt questions over whether our elected representatives are adequately protected when meeting constituents.

       In 2000, Nigel Jones, the former Liberal Democrat MP for Cheltenham, witnessed his assistant Andrew Pennington killed with a Japanese sword after a man called Robert Ashman entered Jones's constituency office wielding the "katana" blade.

       Lord Jones, now a member of the House of Lords, needed 57 stitches to close wounds to his hand from the assault.

       Pennington, a local councillor, was posthumously awarded the George Medal for his attempts to protect Jones.

       Ashman was subsequently found guilty of attempted murder and admitted to Pennington's manslaughter on the grounds of diminished responsibility in 2003.

       Stephen Timms stabbing

       In 2010, Stephen Timms, the Labour MP for East Ham, was stabbed during his constituency surgery by Roshonara Choudhry, a British former student and an Islamic extremist, in an attempt to kill him.

       She was found guilty of attempted murder and jailed for life with a minimum term of 15 years.

       Choudhry, who stated that she had been influenced by online sermons of Anwar al-Awlaki, the leader of Al-Qaeda in the Arabian Peninsula, was the first Al-Qaeda sympathiser to attempt an assassination in Britain.

       Timms suffered "potentially life-threatening" lacerations to the left lobe of his liver and a perforation to his stomach.

       A senior police officer said he was "extremely fortunate not to have been killed."

       He underwent emergency surgery at the Royal London Hospital and was discharged five days later.

       Jo Cox murder

       In 2016, Jo Cox, the Labour MP for Batley and Spen died after being shot and stabbed multiple times in Birstall, West Yorkshire.

       Thomas Alexander Mair, a 53-year-old gardener, was found guilty of her murder and other offences connected to the killing.

       The judge concluded that Mair wanted to advance white supremacism and exclusive nationalism most associated with Nazism and its modern forms.

       He was sentenced to life imprisonment with a whole life order.

       Rosie Cooper targeted

       In 2019, 23-year-old Jack Renshaw was jailed for life for planning to murder Rosie Cooper, the Labour MP for West Lancashire.

       The judge at the Old Bailey said the neo-Nazi had wanted to "replicate" the murder of Miss Cox.

       At the time, Metropolitan Police Commissioner Cressida Dick told a Commons committee threats to MPs were at "unprecedented levels", with the number of crimes reported more than doubling in 2018 - from 151 to 342.

       Heading for 'watershed'

       Describing Sir David as "a very well liked, long-serving MP," Andrew Bridgen, the Tory MP for North West Leicestershire, said MPs were heading for a “watershed".

       "I'm deeply worried about it. I'm pretty outspoken but all MPs have got our social media being monitored by the police.

       "I think if we're not careful we will end up in a situation where we don’t have any surgeries. I think there will be a lot of concern among colleagues about doing surgeries, which would be a loss to democracy."

       In 2019, a BBC investigation found that more than 60 per cent of MPs surveyed had been in contact with police over threats they had received in the previous six months.

       SNP MP Dr Lisa Cameron said she had put in place extra security so her children could play safely in her garden.

       Conservative Scott Mann said someone threatened to nail bomb his office.

       Some MPs had told the authorities they would not run for office again because of safety fears.

       Of the 172 who responded to the BBC's poll, 139 said either they or their staff had faced abuse in the past year.

       More than 60% (108) of those who replied said they had been in contact with the police about threats in the last 12 months.

       Separate analysis carried out by academics at the University of Sheffield for BBC News looked at levels of abuse directed at MPs on Twitter.

       They found that on average, male MPs attracted significantly more abuse than female ones.

       Conservative MPs attracted significantly more abuse than Labour ones while sexist abuse was the most prevalent online, as compared with homophobia or racism.