 as documenting the technical approach taken to building the TFD and its flows of data, this has been less considered: “When I started there was no documentation at all. It was ‘speak to [staff member] or [staff member[’ because they had the knowledge.” (Insight Bristol team) Since it was unclear whether or not the product would be a success, it is understandable that documentation was not initially created. The iterative way in which the TFD was developed also did not lend itself to the standard technical documentation processes within the Local Authority, involving detailed business cases and technical specifications. The Insight Bristol team therefore elected to invest time in product development instead of producing detailed technical documents. “What we were doing was ground-breaking and innovative and that it meant that we didn't have existing documents that we could rely on because it was kind of all new” (Insight Bristol team) However, further into the project, project staff suggested that a lack of documentation in other key areas, such as how the product was built, meant there was a reliance on tacit knowledge held by individuals, which left the TFD vulnerable when these people left. This was particularly relevant to the risk models: “Then [staff member] left and then [staff member] who was building the models also left and So, when he left, there were very little notes. Very few notes on it” (Insight Bristol team) “If there have been changes since it went to the police, I only know that anecdotally. The risk models were developed by a person who left, with various consequences… When people have moved on, we have struggled to navigate, to maintain the consistency of the model from the police end. Then we're using information that is potentially really vulnerab