Fitzwilliam was descended from a Merchant Taylor of London who bought Milton, three-and-a-half miles from Peterborough, in 1502. One seat in the borough was held by the family in most parliaments of Elizabeth’s reign. This influence came to an end when Fitzwilliam’s grandfather, after two terms as lord deputy of Ireland, died in debt to the Crown in 1599. As a younger son, Fitzwilliam enjoyed an annuity of £100, which was doubled on his father’s death. However, this was insufficient to maintain the lifestyle to which he aspired, and his reliance on unscrupulous moneylenders further ruined his family’s fortunes.
In April 1606 Fitzwilliam wrote to the 1st earl of Salisbury (Robert Cecil†) from Florence, thanking him for his licence to travel abroad and promising to make good use of it. During his travels he visited Rome in the company of his cousin (Sir) Edward Barrett*.
Fitzwilliam’s financial position had improved sufficiently by 1630 to allow him to buy 500 acres of salt marshes in Lincolnshire.
