I can answer part of W. M.'s Query, by a reference to a personage who
could not have been very far from being the first instance of the kind
(Query, was she?).
"About this time (1202) Gerard de Camville, his old and
faithful adherent, was restored by John to the possession of
the honours of which he had been deprived by King Richard; and
it is a remarkable circumstance that, on the death of the said
Gerard, in the eighteenth year of the king's reign, his widow,
Nichola Camville (who is described by an ancient historian as
being 'a martial woman of great courage and address') had the
sheriffalty of the county of Lincoln committed to her; which
honourable and important trust was continued to her by a grant
of Henry III.," &c.
The above quotation is taken from Bailey's _Annals of Nottinghamshire_,
now publishing in Numbers (Part III. p. 107.). Should I be wrong in
asking correspondents to contribute towards a list of ladies holding the
above honorable post?