Following reforms in 1999, the automatic right of hereditary peers to sit in the House of Lords was abolished.
Disclaiming a peerage is now an anachronism and in most cases, unnecessary.
Previously, anyone succeeding to a hereditary peerage had the right to disclaim it for life within 12 months of succession.
The usual reason for wishing to do this was to remain a Member of Parliament.
On disclaiming a peerage, the title would have remained in the family and passed on to the next heir on the death of the person who has disclaimed it.
The most famous examples are:-
• Anthony Wedgwood Benn (Tony Benn) who became Viscount Stansgate when his father died in 1960 and was therefore automatically barred from entering the House of Commons in spite of being an elected MP. His determination to return to the Commons resulted in the legislation that made disclaiming a peerage possible;
• Lord Hailsham (Quintin Hogg) who renounced his peerage in 1963 in the hope of becoming Conservative Party leader;
• Lord Home (Sir Alec Douglas-Home) who renounced his peerage on becoming prime minister in 1963.