Tanfield’s father was a younger son in a well-connected Northamptonshire family, three members of which had sat in Parliament in the mid-fifteenth century. Tanfield himself, a professional lawyer, inherited little or nothing, but acquired ex-monastic property in Burford, Oxfordshire, about 16 miles west of New Woodstock, which he represented in the last six Elizabethan Parliaments.
Tanfield was returned as senior Member for Oxfordshire on 7 Mar. 1604 and knighted a week later. He was named to 25 committees during the first session, but is known to have spoken only once. He was appointed to both committees of grievances on 23 Mar. and three days later he was named to the subcommittees for the perusal of the Prayer Book and the drafting of a bill in restraint of purveyance, the abuses of which had doubtless been observed by Tanfield himself when he entertained the king.
Tanfield became a judge shortly before the delayed opening of the second session in 1606, and thereby was disqualified from sitting any longer in the Commons. However, as a Union commissioner, he signed the Instrument of the Union submitted to the English Parliament in November 1606.
Tanfield drew up his will on 21 Mar. 1624. By the following October he was reported to be ‘very infirm’, though he continued to perform his judicial duties at Westminster, being ‘unwilling to seem ill, having never been ill in his life before’.
