In the final episode of Bassie & Adriaan (1978) it is clearly told to Bassie and Adriaan that their mysterious errands were a plan to show the kids about the 12 countries of the then-upcoming European Union, with the explanation that instead of one conductor, there was one for each country. But when receiving a false errand by the Baron, they don't seem to remember anything of this at all.
When the Baron announces he has a new idea to get revenge on Bassie and Adriaan, Harry seems to enjoy the foresight of a new scheme. A few scenes later, when the Baron announces he finished his new revenge plan, Harry's reaction is completely opposite, with him even trying to stay out of it.