///Police decide whether to grant an individual a firearm after judging whether the applicant is fit to own one. This follows a number of checks, which typically include interviews, visits to the person’s property, criminal records checks and references from friends.
They should be able to demonstrate that “they require their firearm on a regular, legitimate basis for work, sport or leisure (including collections or research)”, although police are able to exercise discretion on a case-by-case basis of what merits a “good reason” to own a firearm.
In renewing a certificate, individuals are required by law to disclose their mental health history. Applicants’ GPs may be contacted during the vetting process, and GPs are informed once a certificate has been granted. While people are not required to disclose a related mental health condition during the period their certificate remains valid, doctors have a duty to “disclose information where they believe the patient may present a risk of death or serious harm to themselves or others”.///
https://www.theguardian.com/uk-news/2021/aug/13/what-are-rules-firearms-licences-uk