Complex sentence: Norman Gash is a renowned historian, famous for his peerless biography/analysis of Sir Robert Peel in two volumes; the first of which was entitled "Mr Secretary Peel" and followed his life up until 1830.
Split into simpler sentences: Norman Gash is a renowned historian, famous for his peerless biography/analysis of Sir Robert Peel. The biography is in two volumes; the first of which was entitled "Mr Secretary Peel" and followed his life up until 1830.