Question: Robert Lowther was an English Member of Parliament, and younger brother of ?
Context: The Antrobus Baronetcy, of Antrobus in the County Palatine of Chester, is a title in the Baronetage of the United Kingdom.  It was created on 22 May 1815 for Edmund Antrobus, of Antrobus Hall, Antrobus, Cheshire, a Fellow of the Royal Society, with remainder to his nephews Edmund Antrobus and Gibbs Antrobus.  He died unmarried in 1826 and was succeeded according to the special remainder by his nephew Edmund, the second Baronet.  He and his brother Gibbs were the sons of John Antrobus, brother of the first Baronet.  The second Baronet was succeeded by his eldest son, the third Baronet.  He sat as Member of Parliament for Surrey East and Wilton.  His eldest son, the fourth Baronet, was a Colonel in the Coldstream Guards.  He died without surviving male issue and was succeeded by his younger brother, the fifth Baronet.  Most of the Amesbury Abbey estate in Wiltshire was sold the same year.  The fifth Baronet died unmarried and was succeeded by his first cousin, the sixth Baronet.  He was the son of Robert Crawfurd Antrobus, younger son of the second Baronet.  He was childless and on his death in 1968 the line of the second Baronet failed.  He was succeeded by his second cousin once removed, the seventh Baronet.  He was the eldest son of Edward Geoffrey Antrobus, second son of John Coutts Antrobus, son of the aforementioned Gibbs Antrobus, younger brother of the second Baronet.  As of 2008 the title is held by the seventh Baronet's eldest son, the eighth Baronet, who succeeded in 1995.  He lives in Johannesburg, South Africa. Lord Blayney, Baron of Monaghan, in the County of Monaghan, was a title in the Peerage of Ireland.  It was created in 1621 for the soldier Sir Edward Blayney.  He was succeeded by his son, the second Baron.  He was killed at the Battle of Benburb in 1646.  His younger son, the fourth Baron (who succeeded his elder brother), represented County Monaghan in the Irish House of Commons.  His elder son, the fifth Baron, was attainted by the Parliament of James II for supporting William of Orange.  He had no sons and was succeeded by his younger brother, the sixth Baron.  He was Governor of County Monaghan.  His son, the seventh Baron, was Lord Lieutenant of County Monaghan.  He was succeeded by his elder son, the eighth Baron.  He was a clergyman and served as Dean of Killaloe.  He had no surviving children and was succeeded by his younger brother, the ninth Baron.  He was a Lieutenant-General in the Army.  His younger son, the eleventh Baron (who succeeded his elder brother), was also a Lieutenant-General in the Army and fought in the Peninsular War.  Lord Blayney also represented the rotten borough of Old Sarum in Parliament.  His son, the twelfth Baron, sat as Conservative Member of Parliament for County Monaghan and was later an Irish Representative Peer from 1841 until his death.  On his death in 1874 the title became extinct. Baron Muncaster was a title in the Peerage of Ireland and in the Peerage of the United Kingdom held by the Pennington family.  This family, of Muncaster Castle in Cumberland, descended from William Pennington, who was created a Baronet, of Muncaster in the County of Cumberland, in the Baronetage of England in 1676.  He was succeeded by his son, the second Baronet.  He represented Cumberland in the House of Commons.  His son, the third Baronet, also sat as Member of Parliament for this constituency.  He died childless and was succeeded by his younger brother, the fourth Baronet.  On his death the title passed to his son, the fifth Baronet.  He was Member of Parliament for Milborne Port and Colchester.  In 1783, ten years before he succeeded his father in the baronetcy, he was raised to the Peerage of Ireland as Baron Muncaster, with remainder in default of male issue of his own to his younger brother Lowther Pennington and the heirs male of his body. Robert Lowther (13 December 1681 – September 1745) was an English landowner, holding the estate of Maulds Meaburn, and colonial governor.  He was the eldest son of Richard Lowther and Barbara Prickett. Robert Lowther (1741–1777) was an English Member of Parliament, the younger son of Robert Lowther and Catherine Pennington and younger brother of James Lowther, 1st Earl of Lonsdale. William Lowther (17 June 1668 – 28 July 1694) was an English Member of Parliament, the posthumous son of John Lowther and his second wife, Mary Withins. James Lowther, 1st Earl of Lonsdale (5 August 1736 – 24 May 1802) was an English politician and landowner.  He was a Member of Parliament for over twenty years before, in 1784, he was raised to the Peerage of Great Britain as Earl of Lonsdale. Sir William Godolphin (1547 – October 1589), of Treveneage in Cornwall, was an English Member of Parliament.  He was the younger son of Thomas Godolphin, Captain (governor) of the Scilly Isles, a member of one of Cornwall's leading families, and is wife Katherine Bonithon; his older brother, Sir Francis, who took over the governorship of the Scillies from their father, was also an MP and Vice-Warden of the Stannaries.  Sir William represented Helston, at that period the Godolphin family borough, in the Parliament of 1586–7.  He married Jane Gaverigan on 11 December 1587, only shortly before his death.  His son, Francis, was MP for St Ives in the Long Parliament. Sir Jonathan Trelawny (17 December 1568 – 21 June 1604), of Pool in Menheniot, Cornwall, was an English Member of Parliament.  Trelawny was the posthumous younger son of John Trelawny of Pool (who had been a member of parliament and High Sheriff of the county); his elder brother died in infancy and he inherited the estate.  He entered Parliament as member for Liskeard, representing that borough in three parliaments, and subsequently also represented Cornwall in the Parliaments of 1597 and 1604.  On one occasion he was sent to the Tower of London for losing his temper during a parliamentary debate where he ""dealt his opponent, Mr Ashe, a thundering box to his ear"" and ""flashed his sword"". The Rogers Baronetcy, of Wisdome in the County of Devon, was a title in the Baronetage of England.  It was created in 1699 for John Rogers, a merchant and Member of Parliament for Plymouth.  His son, the second Baronet, and grandson, the third Baronet, also represented Plymouth in Parliament.  The latter was childless and was succeeded by his younger brother, the fourth Baron.  He was a Captain in the Royal Navy.  His son, the fifth Baronet, sat as Member of Parliament for Plymouth.  He was succeeded by his eldest son, the sixth Baronet.  He sat as Member of Parliament for Callington and was also a composer.  He was unmarried and was succeeded by his younger brother, the seventh Baronet.  The latter was succeeded by his eldest son, the eighth Baronet.  He was a prominent civil servant and notably served as Permanent Under-Secretary of State for the Colonies from 1860 to 1871.  In 1871 he was elevated to the Peerage of the United Kingdom as Baron Blachford, of Wisdome and of Blachford in the County of Devon (Blachford House, Cornwood, near Ivybridge).  He died childless in 1889 when the barony became extinct.  He was succeeded in the baronetcy by his younger brother, the ninth Baronet.  The latter was in his turn succeeded by another brother, the tenth Baronet, on whose death in 1895 the baronetcy became extinct as well.
Answer: James Lowther, 1st Earl of Lonsdale