Question: What title is the husband of Philippa Charlotte Middleton heir to?

Context articles: Thomas Stafford, 3rd Earl of Stafford
Baron Milford
Broke-Middleton baronets
Pippa Middleton
Baron Middleton
James Matthews (racing driver)
Baron Cottesloe
Duke of Rothesay
Philippa Baker (rower)
Dia Art Foundation

Thomas Stafford, 3rd Earl of Stafford (c. 1368–4 July 1392) was the second son—but only surviving heir—of Hugh Stafford, 2nd Earl of Stafford and Philippa de Beauchamp, daughter of Thomas de Beauchamp, 11th Earl of Warwick.
 His elder brother, his father's heir, Sir Ralph Stafford, was murdered by Richard II's half-brother, the earl of Huntingdon whilst they were campaigning in Scotland in May 1385.
 As a result, Thomas became heir to the earldom of Stafford, and in 1390 he was knighted.
 He gained livery of his estates in 1391 and paid homage to the king for them on 20 October that year.
 He spent his short career campaigning in France alongside the duke of Gloucester.
Baron Milford is a title that has been created three times, once in the Peerage of Ireland and twice in the Peerage of the United Kingdom.
 All three creations have been for members of the same family.
 The first creation came in the Peerage of Ireland in 1776 when Sir Richard Philipps, 7th Baronet, of Picton Castle was made Baron Milford (there was no territorial designation).
 However, this title became extinct on his death in 1823, while the baronetcy was passed on to a distant relative (see the Viscount St Davids).
 The title was revived in the Peerage of the United Kingdom in 1847 when Sir Richard Philipps, 1st Baronet, of Picton Castle was created Baron Milford, of Picton Castle in the County of Pembroke.
 Born Richard Bulkeley Philipps Grant, he was the son of John Grant and Mary Philippa Artemisia, daughter of James Child and Mary Philippa Artemisia, daughter of Bulkeley Philipps, uncle of the first Baron of the first creation.
 He succeeded to the Philipps estates in 1823 and assumed the surname of Philipps the same year.
 In 1828 he was created a Baronet, of Picton Castle in the County of Pembroke, in the Baronetage of the United Kingdom.
 However, Lord Milford was childless and the titles became extinct on his death in 1857.
 He devised his estates to his half-brother Reverend James Henry Alexander Gwyther, who assumed the surname of Philipps.
 James's daughter Mary Philippa married Charles Edward Gregg, who assumed the surname of Philipps and was created a Baronet, of Picton, in 1887 (see Philipps Baronets).
The Broke, later Broke–Middleton Baronetcy, of Broke Hall in the County of Suffolk, was a title in the Baronetage of the United Kingdom.
 It was created on 2 November 1813 for Philip Broke, a Rear-Admiral of the Royal Navy.
 He was the grandson of Robert Broke, nephew of Sir Robert Broke, 1st Baronet, of Nacton (see Broke Baronets), who were both descended from Sir Richard Broke, Chief Baron of the Exchequer during the reign of Henry VIII.
 The second Baronet was High Sheriff of Suffolk in 1844 and his younger brother the third Baronet was High Sheriff of Suffolk in 1864.
 The third Baronet assumed the additional surname of Middleton in 1860 after inheriting the estate of his cousin Sir William Fowle Fowle Middleton.
 The title became extinct on his death in 1887.
Philippa Charlotte Middleton ( ; born 6 September 1983) is an English socialite, author, columnist, and the younger sister of Catherine, Duchess of Cambridge.
 Middleton began receiving media attention with her appearance as the maid of honour at her sister's wedding to Prince William.
 After marrying James Matthews in 2017, she will be styled Lady Glen Affric should he inherit his father's title.
Baron Middleton, of Middleton in the County of Warwick, is a title in the Peerage of Great Britain.
 It was created in 1711 for Sir Thomas Willoughby, 2nd Baronet, who had previously represented Nottinghamshire and Newark in Parliament.
 The Willoughby Baronetcy, of Wollaton in the County of Nottingham, had been created in the Baronetage of England in 1677 for his elder brother Francis Willoughby, with special remainder to the latter's only brother Thomas, who succeeded him in 1688.
 Lord Middleton was succeeded by his eldest son, the second Baron.
 He sat as Member of Parliament for Nottinghamshire and Tamworth.
 On the death of his younger son, the fourth Baron (who had succeeded his elder brother), the line of the eldest son of the first Baron failed.
 He was succeeded by his cousin Henry Middleton, the fifth Baron.
 He was the son of the Hon. Thomas Willoughby (c. 1694–1742), second son of the first Baron.
 On the death of his son, the sixth Baron, this line of the family also failed.
James Spencer Matthews (born 21 August 1975) is a British former professional racing driver, hedge fund manager, and heir to the Scottish courtesy title of Laird of Glen Affric.
 In 2017, he married Philippa Middleton, younger sister of Catherine, Duchess of Cambridge.
Baron Cottesloe, of Swanbourne and Hardwick in the County of Buckingham, is a title in the Peerage of the United Kingdom.
 It was created in 1874 for the Conservative politician and former Chief Secretary for Ireland, Sir Thomas Fremantle, 1st Baronet (1798–1890).
 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 Berkshire, in 1821, 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).
 Nowadays, John Fremantle, 5th Baron Cottesloe is the current holder of this title, and his son Hon. Thomas Henry Fremantle, heir to the Cottesloe Barony, will be the last future holder being allowed to use the Austrian title in the United Kingdom.
Duke of Rothesay (Scottish Gaelic: "Diùc Baile Bhòid" , Scots: "Duik o Rothesay" ) is a dynastic title of the heir apparent to the British throne, currently Prince Charles.
 It was a title of the heir apparent to the throne of the Kingdom of Scotland before 1707, of the Kingdom of Great Britain from 1707 to 1801, and now of the United Kingdom of Great Britain and Northern Ireland.
 It is the title mandated for use by the heir apparent when in Scotland, in preference to the titles "Duke of Cornwall" (which also belongs to the eldest living son of the monarch, when and only when he is also heir apparent, by right) and "Prince of Wales" (traditionally granted to the heir apparent), which are used in the rest of the United Kingdom and overseas.
 The Duke of Rothesay also holds other Scottish titles, including those of Earl of Carrick, Baron of Renfrew, Lord of the Isles and Prince and Great Steward of Scotland.
 The title is named after Rothesay on the Isle of Bute, Argyll and Bute, but is not associated with any legal entity or landed property, unlike the Duchy of Cornwall.
Philippa June Baker, {'1': ", '2': ", '3': 'MBE', '4': "} (born 12 June 1963), now known by her married name Philippa Baker-Hogan, is a former New Zealand rower and politician.
 She was the first New Zealand woman to win a gold medal at World Rowing Championships and won gold at world championships on two more occasions.
 She has twice represented New Zealand at the Olympics.
 She has received numerous awards for her rowing success and in 2012, she and fellow double sculler Brenda Lawson were inducted into the New Zealand Sports Hall of Fame.
 A trained radiographer, she manages her husband's medical practice.
 She has been a Whanganui District Health Board and Wanganui District Council member since 2004 and 2006, respectively, and was a mayoral candidate in 2010.
 She is a member of the New Zealand Labour Party.
Dia Art Foundation is a nonprofit organization that initiates, supports, presents, and preserves art projects.
 It was established in 1974 as the "Lone Star Foundation" by Philippa de Menil, the daughter of Houston arts patron Dominique de Menil and an heiress to the Schlumberger oil exploration fortune; art dealer Heiner Friedrich, Philippa's husband; and Helen Winkler, a Houston art historian.
 Dia wanted to support projects "whose nature or scale would preclude other funding sources."