With the growth in technology, there is a desire to embrace the increased functionality and capability that it can yield. For large control and indication (C&I) systems on a submarine, this translates to monitoring and automation several orders of magnitude beyond that possible on previous classes. As such, system complexity increases significantly. In addition to ensuring that an individual system operates correctly, it is imperative to ensure that when brought together these complex systems interoperate as intended. Given the spatial complications of a built submarine, and the programmatic implications of correcting defects post-build, it is advantageous to be able to verify and validate correct operation of this super system-of-systems ahead of installation. The methodology described in this paper relates to the novel approach of shore-side integration testing of complex systems as applied to the Dreadnought build programme.