She was a daughter of Anna, King of East Anglia, and her siblings were Wendreda and Seaxburh of Ely, both of whom eventually retired from secular life and founded abbeys.

She was one of the four saintly daughters of Anna of East Anglia, including Wendreda and Seaxburh of Ely, all of whom eventually retired from secular life and founded abbeys.

One account relates that while Ecgfrith initially agreed Æthelthryth should continue to remain a virgin, about 672 he appealed to Wilfrid for the enforcement of his marital rights as against Etheldreda's religious vocation.

[1] Eventually, in light of the danger of being forcibly carried off by the king, Æthelthryth then fled back to the Isle of Ely with two nuns as companions.

According to Bede, Æthelfryth died of a neck tumour, which she interpreted as sent by God in his goodness to relieve her of guilt for her vanity in having worn heavy necklaces in her youth.

[6] Bede states that after her death, her bones were disinterred by her sister and successor, Seaxburh and that her uncorrupted body was later buried in a white, marble coffin.

[9] She apparently oversaw the translation of her sister's remains without the supervision of her bishop, using her knowledge of procedures gained from her family's links with the Faremoutiers Abbey as a basis for the ceremony.

The church has a small Mediaeval English stained-glass window, depicting St Etheldreda, which is set in a stone frame made from a very early Insular Christian Roman Chi Rho grave marker.

By the 17th century, this lacework had become seen as old-fashioned, vain, or cheap and of poor quality, at a time when the Puritans of eastern England disdained ornamental dress.