The fatal shooting and stabbing of Labour MP Jo Cox has reignited an ongoing debate about security for politicians across the UK.
While MPs are protected by high security measures when they are in Parliament, it is a different matter when they are in their constituencies.
Parliament issues security advice to all MPs, and politicians can claim a separate allowance for security measures in their constituency offices.
However, there does not appear to be a blanket one-size-fits-all security policy for all MPs and their employees.
According to the Working for an MP website, which is used by MPs’ staff, those who work in constituency offices are encouraged to develop an office code for potentially dangerous or disruptive situations.
One former employee of an MP wrote on the site: "A constituency office I worked in has a code for calling the police in the event of a violent visitor - the secretary would call the caseworker in the back room [with a certain phrase]."
In 2010, security measures for MPs were updated after Labour MP Stephen Timms was stabbed twice in the stomach by a constituent in Beckton, east London.
And in January, the Independent Parliamentary Standards Authority (Ipsa) announced MPs were to get an "enhanced" security package following protests outside MPs' constituency offices over the House of Commons vote on bombing Syria.
Under the rules, MPs can apply for a standard package of measures which allow them to buy or lease security equipment such as alarm systems, CCTV and personal alarms.
MPs can also claim the cost of security measures they feel is appropriate to the threats they face after consulting with their local police.
On Friday, 10 Downing Street sent a security reminder to all MPs, following Jo Cox's fatal attack.
The advice includes steps politicians can take to stay safe when they are out in public, and suggests they should contact local police if they have any security concerns.