Gascon was the manager of the "Tomato Greenhouse."
The Tomato Greenhouse referred to the garden area located northwest of the closed black palace, which was where the official residence of Charlotia's ruler. Being the manager of the Tomato Greenhouse was no different from being called Charlotia's top gardener.
The reason Gascon wasn't called the royal gardener was that Charlotia no longer had a royal family.
The royal people had been executed, the palace closed, and the queen had disappeared.
Gascon was the top candidate to be called the royal gardener on the day the missing Queen Charlotte returned. Every time he entered the official residence, he would imagine himself as the royal gardener.
However, the queen who had disappeared before he turned 10 had not been found even when he was over 60 years old. Queen Charlotte was now considered a character from a fairy tale used to explain why this country was called "Charlotia."