| Orr-Ewing (Barony) |
Charles Ian Orr-Ewing - Fri 30th Apr 1971
|
19 August 1999 |
- |
| Orwell (Viscountcy) |
Francis Vernon - Sun 21st Jul 1776
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- |
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| Orwell (Barony) |
Francis Vernon - Wed 7th Apr 1762
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- |
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| Osamor (Barony) |
Martha Otito Osamor - Mon 26th Nov 2018
|
- |
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| O'Shaughnessy (Barony) |
James Richard O'Shaughnessy - Thu 1st Oct 2015
|
- |
- |
| Ossington (Viscountcy) |
John Evelyn Denison - Tue 13th Feb 1872
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7 March 1873 |
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| Ossulston (Barony) |
John Bennet - Tue 24th Nov 1682
|
- |
- |
| Ouseley (Barony) |
Herman George Ouseley - Tue 26th Jun 2001
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- |
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| Overstone (Barony) |
Samuel Jones Loyd - Tue 5th Mar 1850
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17 November 1883 |
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| Overtoun (Barony) |
John Campbell White - Fri 23rd Jun 1893
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15 February 1908 |
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| Owen (Barony) |
David Anthony Llewellyn Owen - Tue 30th Jun 1992
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- |
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| Oxburgh (Barony) |
Ernest Ronald Oxburgh - Tue 27th Jul 1999
|
- |
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| Oxenbridge (Viscountcy) |
William John Monson - Fri 13th Aug 1886
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16 April 1898 |
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| Oxenfoord (Barony) |
John Dalrymple - Mon 16th Aug 1841
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- |
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| of Oxford and Asquith (Earldom) |
Herbert Henry Asquith - Mon 9th Feb 1925
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- |
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| of Oxford and Mortimer (Earldom) |
Robert Harley - Sat 23rd May 1711
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- |
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| of Oxfuird (Viscountcy) |
James Makgill - Wed 19th Apr 1651
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- |
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| Oxmantown (Barony) |
Richard Parsons - Wed 2nd Jul 1681
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- |
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| Oxmantown (Barony) |
Laurence Harman Harman - Sat 22nd Sep 1792
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- |
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| Oxmantown (Viscountcy) |
Laurence Harman Harman - Fri 2nd Oct 1795
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