Past master countable noun
The noun is usually followed by "in/of/at (something)."
Used to refer to someone who is highly skilled or extremely experienced in a particular activity.
James is known as a past master at reading people's mind.
The politician is a real past master of manipulating press and media.
He is studying postgraduate diploma to become a past master of analyzing data.
The plural form of "past master" is "past masters".
This expression most likely refers to someone who has previously held the position of master in a lodge or another organization. Although in the mid-1800s, the term "past mistress" was used to describe an exceptionally skilled woman, it is now less commonly used, with "master" being used for both sexes. [The mid-1800s]
Small and steady efforts can bring about big results.
Little strokes fell great oaks, I've finally accomplished that project.