However, from the 16th century onwards in Cambridge it was used to denote those holding "chairs" that had been founded by the university in a particular subject or endowed by a benefaction.
The university historically has made no formal distinction between established (or statutory) chairs and personal (or titular) chairs: all professorships are university offices formally established by a vote, and listed together as one class in the statutes.
In practice, professorships can be established for a limited period of time or for a single tenure only, expiring after the first incumbent vacates office.
It is common for permanent professorships to have originally been established for a single tenure, before being made permanent at a later date.
This article only lists professorships which have had more than one incumbent, or which are not limited in duration.