Gun licence applicants will be required to undergo medical checks as part of new measures introduced following the Plymouth shooting.
The home secretary announced that doctors will have to assess the mental health of those applying for a firearms licence and tell police whether candidates have “any relevant medical conditions”.
Priti Patel said police will have a “legal duty” to consider the new statutory guidance when it is published in the coming weeks.
“We must do all that we possibly can to avoid something like this happening again,” she said.
All forces in England and Wales have been asked to review their current firearm application processes and assess whether they need to revisit any existing licences after police came under criticism for allowing the Plymouth attacker to own a gun.
In a 12-minute rampage on Thursday evening, Jake Davison, 22, killed five people, including his mother and a three-year-old girl, with a shotgun before taking his own life.
The apprentice crane operator had used a local telephone helpline during the pandemic to request mental health support.
Prospective gun owners will also have their social media activity reviewed amid concerns that Davison’s accounts suggested an obsession with “incel” culture.
The “involuntarily celibate” online movement involves men who express hostility and extreme resentment towards those who are sexually active, particularly women.
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The subculture has now been associated with at least six mass shootings and the murder of 46 people in the US.
Davison’s YouTube account also showed that he had liked several videos related to guns and had subscribed to channels with firearms content, including “God family and guns” and “The Gun Collective”.
The police watchdog is already investigating the Devon and Cornwall force over Davison’s possession of a shotgun and shotgun certificate, which were returned to him last month.
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They had been confiscated last December following an assault three months earlier.
In a written statement to Parliament, Ms Patel said the new rules draw on “previous lessons learned” and “will ensure better consistency and improved standards across police firearms licensing departments”.
“The UK has some of the strictest gun control legislation in the world and comparatively low levels of gun crime,” she said.
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Who is Jake Davison?
“Yet while tragedies like last Thursday’s are rare, their impact is profound.
“We constantly assess what sensible and proportionate steps we can take to help prevent such terrible loss of life.”
She said police continue to investigate whether Davison’s rampage was terrorism-related amid calls for it to be reclassified as a terror attack due to its links with the incel movement.
The home secretary said the legal definition is “sufficiently broad” to “capture modern causes of terrorism, including ‘incel’ violence” – but that the decision is for police, not the government.