Under the Peerage Act of 1963 it is possible to disclaim an hereditary peerage of England, Scotland, Great Britain, or the United Kingdom for life. The disclaimer is irreversible, and operates from the date by which an instrument of disclaimer is delivered to the Lord Chancellor.
When a peerage has been disclaimed, no other hereditary peerage may be conferred. Most recently Lord James Douglas-Hamilton, Member of Parliament for Edinburgh West, succeeded as 11th Earl of Selkirk on 23 November 1994 and disclaimed this title for life five days later in order to keep his seat in the House of Commons. When he gave up his parliamentary seat in 1997 he was created a life peer as Baron Selkirk of Douglas.
As soon as a peer has disclaimed his peerage he reverts to the status held before he inherited the title, and he is not accorded any courtesy title or style which he previously possessed deriving from that peerage.
Even though he disclaims the peerage within a few days after succession he must first have succeeded as a peer immediately on his predecessor's death, and for that interval he will figure in the numbering in works of reference, eg 11th Earl of Selkirk.
Should he also be a baronet or knight, these dignities and appropriate styles are retained, being unaffected by his disclaiming the peerage.
Example: Rt Hon Tony Benn (formerly Viscount Stansgate).
A life peerage cannot be disclaimed.