He succeeded his father in 1630 and was appointed High Sheriff of Northamptonshire for 1639-40.

He is recorded as being the High Sheriff of Northamptonshire in 1851.

Sir William was Sheriff of Northamptonshire in 1518, 1522, 1534 and 1538.

He was Sheriff of Northamptonshire from 1632 to 1633.

Mildmay was High Sheriff of Northamptonshire for 1580 and 1592.

He was knighted in 1660 and appointed Sheriff of Northamptonshire for 1664.

He was High Sheriff of Northamptonshire in 1599 and in 1618.

He also served as High Sheriff of Northamptonshire in 1568-1569 and 1581-1582.

In 1881 he was appointed high Sheriff of Northamptonshire.

He was appointed High Sheriff of Northamptonshire for 1551-52, 1558-59, 1571-72 and 1583-84.