Complex sentence: Robert Devereux, 16th Viscount Hereford (3 January 1843--27 March 1930) was a British aristocrat who succeeded to the oldest extant viscountcy in the Peerage of England, sitting in the House of Lords as Premier Viscount of England.
Split into simpler sentences: Robert Devereux, 16th Viscount Hereford (3 January 1843--27 March 1930) was an English Peer. The Viscountcy of Hereford is the oldest extant viscountcy in the Peerage of England, making the holder the Premier Viscount of England.