At Hertling, since 1910, with Friedrich Wilhelm Albert Viktor of Prussia, at least a real king and also an emperor was customer, because the Hertling removals company had been the court forwarder of His Majesty the Emperor and King of Prussia since 1910. (https://de.wikipedia.org/wiki/Liste_preußischer_Hoflieferanten).
But to this day, the customer of our moving company is still king (... but he likes to listen to our professional advice 😊). And sometimes we are still allowed to move our customers into a castle! As just happened when we were allowed to perform the move from Berlin to France for a client who actually moved into a chateau.