[4] Percy was the second son of Sybella Augusta (née Milbank) Herbert and Maj.-Gen. Hon.

His maternal grandparents were Mark William Vane Milbank (grandson of William Vane, 1st Duke of Cleveland) and Barbarina Sophia Farquhar (a daughter of Sir Thomas Farquhar, 2nd Baronet).

He held the office of Bishop of Norwich between 1942 and 1959,[5] where he presided over a number of prominent weddings, including Lady Anne Coke and Colin Tennant in 1956.

[8] After retiring from his post as Bishop of Norwich, Herbert became Rector of St Mary Magdalene's Church in Sandringham.

He was Clerk of the Closet to King George VI from 1942 to 1952 and then to Queen Elizabeth II from 1952 to 1963.