The SATRE DARE UK-funded Driver Project was challenged to create a trusted research environment (TRE) architecture supporting the research community's need to have suitable data analytics and research environments for working with sensitive data. The project developed an inclusive and transparent way of working to ensure that what was created was representative of the TRE community in the UK. We have created, for the first time, an open specification for TRE operators by which to evaluate themselves against a set of capabilities. It is a thorough specification, perhaps definition, for TREs informed not only by the experience of the project team who have been running a TRE and supporting sensitive data projects for a combined 15 years but also the expansive knowledge of the wider UK research community. The public has also been involved throughout the development of the specification to ensure their voices are heard and reflected in the specification. The specification has been informed through one survey completed by 105 individuals representing approximately 60 organisations, 14 Collaboration Cafés with up to 75 participants, 26 individuals contributing directly, 44 issues raised and six public engagement sessions online and in-person. Despite the breadth and diversity of the individuals included, we have been able to create a single specification encompassing four architectural principles, four pillars, 29 capabilities and 160 statements. The 75 mandatory statements are what is considered the minimum required to be a SATRE-compliant TRE. Now, with a stable version 1.0 release, the specification is ready for use by the UK TRE community. We are and will continue to work with all organisations to evaluate themselves against the specification and also identify what works and what doesn't, which will be captured in future versions of the specification. The specification has been developed with the long-term in mind and can be a basis for a common understanding between operators, data controllers, accreditors, researchers, industry and government organisations for how TREs can federate and interoperate better. This work was funded by UK Research & Innovation [Grant Number MC_PC_23008] as part of Phase 1 of the DARE UK (Data and Analytics Research Environments UK) programme, delivered in partnership with Health Data Research UK (HDR UK) and Administrative Data Research UK (ADR UK).