In late 1560 Lettice Knollys married Walter Devereux, Viscount Hereford. The couple lived at the family seat of Chartley in Staffordshire. Here the two eldest of their five children, the daughters Penelope and Dorothy, were born in 1563 and 1564, respectively. Lettice Devereux returned to court on at least one occasion, in the summer of 1565, when the Spanish ambassador Diego Guzmán de Silva described her as "one of the best-looking ladies of the court" and as a favourite with the Queen. Pregnant with her first son, she flirted with Robert Dudley, Earl of Leicester, the Queen's favourite. The Queen found out at once and succumbed to a fit of jealousy. The Viscountess went back to Staffordshire where, in November 1565, she gave birth to Robert, later 2nd Earl of Essex. Two more sons followed: Walter, who was born in 1569, and Francis, who died soon after birth at an unknown date.