Baron Cottesloe, of Swanbourne and Hardwick in the County of Buckingham, is a title in the Peerage of the United Kingdom. It was created on 2 March 1874 for the Conservative politician and former Chief Secretary for Ireland, Sir Thomas Fremantle, 1st Baronet (1798–1890).^[1] He was the son of Admiral Sir Thomas Fremantle (1765–1819). Lord Cottesloe had already been created a Baronet, of Swanbourne in the County of Buckingham, on 14 August 1821,^[2] chiefly in recognition of his father's services, and with remainder to the latter's heirs. His father Sir Thomas Fremantle was created Baron Fremantle, of the Austrian Empire, which Lord Cottesloe inherited in 1819 with the death of his father. Subsequently, in 1822 he was given a Royal licence, which authorized him and his successors to use the title in Britain. However, a warrant issued on 27 April 1932 withdrew all the royal licences, only allowing the use of the title to the then current holders, their heir (if any was born) and their heir's heir (if any was born). The fifth baron was the last holder being allowed to use the Austrian title in the United Kingdom.^[3][4]

The 1st Baron Cottesloe was succeeded by his eldest son, Thomas Fremantle, 2nd Baron Cottesloe. He represented Buckinghamshire in the House of Commons as a Conservative. His son, the 3rd Baron, served as Lord Lieutenant of Buckinghamshire. The latter's grandson, the fifth Baron, who succeeded his father in 1994, also served as Lord Lieutenant of Buckinghamshire between 1984 and 1997. As of 2018^[update], the title is held by his son, the sixth baron, who succeeded in that year.

Several other members of the Fremantle family have also gained distinction. William Henry Fremantle, uncle of the first Baron, was a politician. John Fremantle, son of Colonel Stephen Fremantle, uncle of the first Baron, was a major-general in the army. He was the father of 1) General Sir Arthur Fremantle and of 2) FitzRoy William Fremantle, a major-general in the Coldstream Guards. Sir Charles Fremantle, brother of the first Baron, was a naval commander. The town of Fremantle, Western Australia, is named after him. The Very Reverend the Hon. William Robert Fremantle, brother of the first Baron, was Dean of Ripon. The Very Reverend the Hon. William Henry Fremantle, second son of the first Baron, was Dean of Ripon and Canon of Canterbury. His second son Sir Francis Edward Fremantle was a Conservative politician. The Hon. Sir Charles Fremantle (1834–1915), third son of the first Baron, was an administrator with the Suez Canal Company. The Hon. Sir Edmund Fremantle, fourth son of the first Baron, was an admiral in the Royal Navy. He was the father of 1) Admiral Sir Sydney Fremantle and 2) Sir Selwyn Fremantle, an administrator in India.

• Admiral Thomas Francis Fremantle, 1st Baron Fremantle (1765–1818)

• Sir Thomas Francis Fremantle, 1st Baronet, 2nd Baron Fremantle (1798–1890), created Baron Cottesloe in 1874

• Thomas Francis Fremantle, 1st Baron Cottesloe, 2nd Baron Fremantle (1798–1890)
• Thomas Francis Fremantle, 2nd Baron Cottesloe, 3rd Baron Fremantle (1830–1918)
• Thomas Francis Fremantle, 3rd Baron Cottesloe, 4th Baron Fremantle (1862–1956)
• John Walgrave Halford Fremantle, 4th Baron Cottesloe, 5th Baron Fremantle (1900–1994)
• John Tapling Fremantle, 5th Baron Cottesloe, 6th Baron Fremantle (1927–2018)
• Thomas Henry Fremantle, 6th Baron Cottesloe (born 1966)

The heir presumptive is the present holder's half uncle Hon. Edward Walgrave Fremantle (born 1961)
The heir presumptive's heir apparent is his son Henry John Fremantle (born 1996)

• Hesilrige, Arthur G. M. (1921). Debrett's Peerage and Titles of courtesy. London: Dean & Son. p. 236.
• Kidd, Charles, ed. (1903). Debrett's peerage, baronetage, knightage, and companionage. London: Dean and son. p. 260.

v t e Extant hereditary baronies in the Peerage of the United Kingdom
King George III	Ellenborough Manners
The Prince Regent	Churchill Harris
King George IV	Ravensworth Delamere Forester Rayleigh Gifford Feversham Seaford Plunket Heytesbury Skelmersdale Wynford
King William IV	Kilmarnock Poltimore Mostyn de Saumarez Denman Abinger Ashburton Hatherton Stratheden Lovat^*
Queen Victoria	Rossmore^• Carew^• de Mauley Wrottesley Sudeley Methuen Stanley of Alderley^• Leigh Monteagle of Brandon Campbell Vivian Congleton Eddisbury^• Londesborough de Freyne Raglan Belper Chesham Churston Leconfield Lyveden Brougham and Vaux Westbury Annaly Northbrook Hartismere^• Hylton Penrhyn O'Neill Napier of Magdala Dunning^* Acton Wolverton O'Hagan Sandhurst Ettrick^* Aberdare Moncreiff Coleridge Cottesloe Hampton Harlech Tollemache Gerard Sackville Norton Trevor Ampthill Derwent Hothfield Tennyson Strathspey Monk Bretton Northbourne Northington^• Rothschild Revelstoke Monkswell Ashbourne St Oswald Montagu of Beaulieu Elphinstone^* Hindlip Grimthorpe Kensington^• Hamilton of Dalzell St Levan Basing de Ramsey Addington Savile Ashcombe Crawshaw Amherst of Hackney Newton Dunleath Swansea Aldenham HolmPatrick Burton Glanusk Cranworth Avebury Killanin Strathcona and Mount Royal
King Edward VII	Kinross Shuttleworth Grenfell Redesdale Burnham Biddulph Ritchie of Dundee Hemphill Joicey Nunburnholme Swaythling Blyth Marchamley Gorell Fisher Kilbracken
King George V	Hardinge of Penshurst de Villiers Glenconner Aberconway Merthyr Rowallan Ashton of Hyde Ravensdale Hollenden Parmoor Cunliffe Wrenbury Faringdon Shaughnessy Rathcreedan Somerleyton Carnock Beaverbrook Gainford Forteviot Colwyn Gisborough Morris Cawley Terrington Glenarthur Phillimore Inverforth Sinha Cochrane of Cults Clwyd Russell of Liverpool Swinfen Meston Cullen of Ashbourne Trevethin Glendyne Manton Forres Vestey Borwick Maclay Bethell Hunsdon Darling Banbury of Southam Merrivale Bradbury Mereworth^• Greenway Hayter Cornwallis Daresbury Wraxall Remnant Moynihan Craigmyle Dulverton Luke Alvingham Baden-Powell Ponsonby of Shulbrede Dickinson Noel-Buxton Howard of Penrith Rochester Selsdon Moyne Davies Rankeillour Brocket Milne Rennell Mottistone Iliffe Palmer Rockley Elton Wakehurst Hesketh Tweedsmuir Wigram Riverdale May Kennet Strathcarron
King Edward VIII	Catto
King George VI	Windlesham Mancroft McGowan Denham Rea Cadman Kenilworth Pender Roborough Brassey of Apethorpe Stamp Bicester Milford Hankey Harmsworth Rotherwick Glentoran Tryon Croft Teviot Nathan Reith Kindersley Ironside Latham Wedgwood Geddes Bruntisfield Brabazon of Tara Keyes Hemingford Moran Killearn Dowding Gretton Westwood Hazlerigg Hacking Chetwode Sandford Altrincham Broadbridge Mountevans Lindsay of Birker Piercy Chorley Calverley Tedder Colgrain Darwen Lucas of Chilworth Shepherd Newall Oaksey Rugby Layton Simon of Wythenshawe Kershaw Trefgarne Crook Amwell Milverton Clydesmuir Burden Haden-Guest Silkin§ Hives Ogmore Morris of Kenwood Macpherson of Drumochter Kenswood Freyberg Milner of Leeds Kirkwood Wise
Queen Elizabeth II	Jeffreys Rathcavan Baillieu Grantchester Coleraine Harvey of Tasburgh Gridley Strathalmond Strathclyde Clitheroe McNair Colyton Astor of Hever Sinclair of Cleeve Bridges Norrie Birkett Harding of Petherton Poole Rootes Netherthorpe Crathorne Spens MacAndrew Nelson of Stafford Howick of Glendale Sanderson of Ayot Cobbold Robertson of Oakridge Marks of Broughton Fairhaven Leighton of St Mellons Brain Aldington Inchyra Silsoe Egremont Thomson of Fleet Martonmere Sherfield Inglewood Glendevon Grimston of Westbury Renwick St Helens Margadale
§: Disclaimed.  Italics: This title is held by a peer who holds another of higher precedence. ^* Also a Lord in the Peerage of Scotland  ^• Also a Baron in the Peerage of Ireland