Definitions for old school
Random House Webster's College Dictionary
advocates or supporters of established custom or of conservatism.
Origin of old school:
a class of people favoring traditional ideas
A style, way of thinking, or method for accomplishing a task that was employed in a former era, remembered either for its inferiority to the current method, or for its time-honored superiority over the new way.
Characteristic of a style, outlook, or method employed in a former era, remembered either as inferior to the current style, or alternately, remembered nostalgically as superior or preferable to the new style, the older denoting something that would be considered out of date or out of fashion to some, but as such, is considered by others as cool and hip.