[1] He was the eldest son, and heir, of Sir Thomas Sadleir (c. 1536 – 1607), lord of the manor of Standon, by his second wife, Gertrude, daughter of Robert Markham, of Cotham, Nottinghamshire.

[3][4] Standon Lordship, the manor house where the couple lived after their marriage, was built for his grandfather and namesake, the statesman, Sir Ralph Sadler (or Sadleir) (1507–1587).

[5] Sadleir delighted in hawking, hunting and the pleasures of country life; was famous for his noble table, his hospitality to his neighbours, and his charity to the poor.

"To-morrow morning we will meet a pack of otter dogs of noble Mr. Sadler's, upon Amwell Hill, who will be there so early, that they intend to prevent the sun rising.

Ralph Sadleir states that he will have the otter's skin, worth 10 shillings, for gloves "the best defence against wet weather".