He ducal court was not noted for the strictness of its morals; the duke was a man of gallantry, and it was rumoured that the duchess followed her husband's example. what is implied in this sentence, without being directly stated?

In this extract from Lytton Strachey's Victoria: Portrait of a Queen, it is implied that the duke and duchess of this ducal court (specifically Ernest III, Duke of Saxe-Coburg-Saalfeld, and his first wife, Louise of Saxe-Gotha-Altenburg, the parents of Prince Albert, the husband of Queen Victoria of England) were not faithful to each other, since the Duke was "a man of gallantry" - a polite or diplomatic way of saying that he enjoyed flirting with women -  and it was believed that his wife "followed his example," that is, that she also flirted with men. Theirs was indeed a very turbulent and unsuccessful marriage, and they eventually divorced and married other people.  

true

coz they had the rank system in society according to the economic power of the people

the answer to your question is:

strong-mayor system