The Their Finest Hour: Battle of Britain Mission Disk is an expansion pack that enhances the original World War II flight simulation game. This add-on content injects new life into the base game by providing 23 additional missions, offering players fresh challenges and scenarios to test their aerial combat skills in the context of the historic Battle of Britain.

A key feature of this expansion is the inclusion of one experienced pilot for each aircraft type available in the game. These veteran pilots likely come with enhanced abilities or characteristics, allowing players to experience missions from the perspective of seasoned airmen. This addition not only increases the gameplay variety but also adds a layer of historical authenticity to the simulation, as it reflects the importance of experienced pilots during the actual conflict. By expanding the mission roster and introducing these skilled pilots, the Mission Disk aims to deepen the strategic depth and replayability of Their Finest Hour: The Battle of Britain, providing enthusiasts with more content to explore in this acclaimed World War II flight sim.