This is a review of safety certification and approval process within UK defence systems and forms part of a set of papers describing certification regimes across a number of industries for the Safety-critical Systems Symposium 2013. Since the range of transportation and infrastructure used within the defence sector draws from all other environmental domains combined, the safety regimes of each UK defence system reflects the civil domains they are drawn from. For this reason, the paper describes the system safety regime within UK warships, including their software-intensive systems.