The series intends to follow the history of the 50s/60s and 70s, and does so closely. The characters however don't evolve at all, which is partly why it remains funny. Jaap Kooyman will always remain a conservative man who doesn't understand a bit of 'modern times'. He will also always do anything to get a promotion at the RET (Rotterdam Public Transport), and always fail. The funny thing also is, when Gerard Cox, the actor in this role, is interviewed for a magazine, or a television, it looks like in this series he is playing himself. Jaap Kooyman is not so much different from Gerard Cox. If Jaap Kooyman would really start to be friendly to homosexuals, or to immigrant workers, the series would be over. Let's hope he doesn't do so, and the series will continue until they hit 1993, when it all started.