What Comes Next? (quiz round 2)

A ten-question quiz round devised by @MrAllsopHistory on behalf of TMHistoryIcons.
This round featured in #TMHIQuiz Number 2, which you can play in realtime on YouTube by clicking here.
This isn’t ripped off from Only Connect…honest! You’re given four things that are related in some way, and your job is to write the next (the fifth) part answer in the sequence.
Click here to view or download. The PDF consists of two pages – a team sheet and the answers.
Please leave a comment below