A professor is addressed by name, Professor Jonathan Johnston, for example.
Should a professor be in Holy Orders, he or she is addressed as the 'Reverend Professor Jonathan Johnston', and is known verbally as 'Professor Johnston'.
When a professor retires from his or her chair at a university, and emeritus rank is conferred, the professor emeritus (or emeritus professor) continues to be addressed as before.
Should a professor be a canon (or have a higher ecclesiastical rank), he or she is sometimes known as 'Professor Johnston', but strictly speaking the ecclesiastical rank supersedes the academic. Thus, a canon should be known as 'Canon Johnston' rather than as 'Professor Johnston', but in practice this is a matter of personal choice.
The academic style is used more often within a university, and the ecclesiastical style outside, but the academic and ecclesiastical styles may be combined as 'The Reverend Professor Jonathan Johnston'. The form 'The Reverend Canon Professor Jonathan Johnston' is never used as it is too cumbersome.
If a professor is also a member of the peerage, or a knight or dame, the academic style and title may be combined as ‘Professor Lord Johnston’ or ‘Professor Dame Elizabeth Jones’. He/she may prefer to be known by title alone.
How to Address a Professor
The recommended form address is:
|Beginning of letter||Dear Sir/Madam (formal); Dear Professor Johnston (social). If a peer, Dear Lord or Lady Kirkcudbright; if a knight, Dear Sir Henry; if a dame, Dear Dame Mary|
|Envelope||Professor Jonathan Johnston*|
|Verbal communication||Lord or Lady Blank; Professor Johnston; etc|
* In social usage it is not uncommon to find crown honours combined with styles emanating from other sources, eg Professor Lord Johnston, although this is deprecated by purists.