MSC stated that children cruise free on all their cruise ships but I am not sure if the rule applies all year round or just at 'off peak' period.
Please ignore the answer below. I misread your question.
Thomson Calypso is adults only and they do occasionally have child free cruises on their other ships....I seem to remember that either Spirit or Celebration has June and September allocated to adults only this year...think I read it on their website.
Why do you ask? I have been on many cruises and having a children on board doe's not in any devalue the cruise. I would ask you to recall the days you were a child and the magical moments you experienced when growing up. I have the utmost respect for elderly citizens but have found a minority amongst themo be worse than children,so maybe I should be descrimate against anyone over 55 years of age, but no I will take my chances.