Complex sentence: Lady Mabel Florence Harriet Wentworth-Fitzwilliam (14 July 1870--26 September 1951) was an English socialist politician, often known as Lady Mabel, and a pioneer in education and social welfare.
Split into simpler sentences: Lady Mabel Florence Harriet Wentworth-Fitzwilliam (14 July 1870--26 September 1951). Known as Lady Mabel, she was an English socialist politician and a pioneer in education and social welfare.