John Priestland is a British advocate who founded and chairs uNHIdden, a nonprofit that treats UAP experiences and a possible disclosure of non-human intelligence as public-health questions. The organization describes itself as led by doctors and clinical psychologists, and it operates through a London-based foundation and a U.S. affiliate, Unhidden Inc. Priestland has argued publicly that governments and health services should plan for how people might react if such a disclosure occurred.

When The Debrief introduced the initiative in November 2023, it described Priestland as a physicist and former UK civil servant working alongside clinical psychologist Daniel Stubbings, with the aim of promoting good mental health and reducing anxiety about non-human intelligence. In April 2024 uNHIdden published a white paper on how exceptional experiences and disclosure affect mental health and wellbeing. Speaking at a Durham University event on SETI and UAP in April 2025, Priestland presented the group's argument that stigma shapes how the subject is discussed, citing a survey in which 69 percent of academic faculty said they worried that UAP research would bring ridicule.

His most substantial work is "Preparing for Disclosure: A Public Health Framework for Paradigm-shifting Revelations," which uNHIdden released in June 2026. The report builds on a health needs assessment that Priestland co-wrote with Gabriel G. De la Torre and Tim Lomas, and it models three scenarios: a distant biosignature, an intelligent signal from far away, and non-human intelligence closer to home. It uses ontological shock as a working label rather than a clinical diagnosis, and it calls for simulation exercises and for disclosure preparedness to be considered in the UK national risk register and in U.S. emergency planning.

The report brought Priestland a wider audience. With physician Martin Abbas he appeared on Ross Coulthart's NewsNation program Reality Check, discussing the psychology of first contact and, in a second segment, the 1953 Robertson Panel, which they cast as an early case of official ridicule damaging public trust. He also discussed the framework on That UFO Podcast and, in August 2026, with Caleb Mayo of WTUFO.

Priestland's significance lies in his effort to move part of the disclosure debate away from secret programs and crash claims toward health systems, clinicians and emergency planners. Through uNHIdden he has argued that preparedness is worthwhile whether or not disclosure happens, and his June 2026 framework, which NewsNation described as the first systematic public-health framework for a disclosure event, set out in detail what such planning would ask of clinicians and governments.