The national history of the commemorative plaque scheme began in the early 1860s.  Following a series of letters in “The Builder” and the “Journal of the Society of Arts”, a scheme was proposed and in 1867 the Royal Society of Arts erested the first plaque, in London, to Lord Byron.  The purpose of a plaque was to celebrate the connection between an illustrious individual and a building in which he/she had lived, worked or died. The principle continues that plaques can only be placed on the actual building inhabited by the nominated person, and not on the site where it once stood.  Only one plaque per person, despite them having ad several addresses, is permitted.
English Heritage assumed responsibility for the scheme in 1986, with a remit to broaden its scope to beyond London and out across the country.

Criteria for UK persons
Must have been dead for twenty years or 100 years since birth, to give time for their reputation to be established.
Must be recognised by their own profession.
Must have contributed to human welfare and happiness.
Must be recognised by well-informed passer-by or have received national recognition e.g. inventors.

Criteria for overseas visitors
Must have an international reputation . Time spent in the location must have been significant within their life/work.

Newcastle-under-Lyme Civic Society follow broadly similar guidelines in their Blue Plaque scheme.