She was the daughter of Sir John Spencer of Althorp and his wife, the former Katherine Kitson.
A revised version of Edmund Spenser's poem, "Mother Hubberd's Tale", published in 1590, was dedicated to Anne as "the Lady Compton and Mountegle".
[3] Anne married the future earl on 4 December 1592, a year after the death of his first wife, the former Lady Margaret Howard.
Whereas his first marriage had been a happy one, he described his second wife in his will as one "whom without great grief and sorrow inconsolable I cannot remember, in regard of her exceeding unkindness and intolerable evil usage towards myself and my late good lord and father deceased".
[5] In March 1610 Anne, Countess of Dorset, argued and fought with officers sent to administer Lord Compton's estate, and was sent to the Fleet Prison.