From The History and Antiquities of the County Palatine of Durham by William Hutchinson (Newcastle: S. Hodgson, 1787), page 493:

The Staiths called FATFIELD STAITHS exhibit a busy scene in the coal trade, where the keels come up to receive their loading for the port of Sunderland. The village is very populous. Near this place is an eminence called the Worm Hill, which tradition says was once possessed by an enormous serpent, that wound its horrid body round the base; that it destroyed much provision, and used to infest the Lambton estate, till some hero of that family engaged it, cased in armour set with razors, and when it would have crushed the combatant by enfolding him, sustaining a thousand wounds, fell at last by his falchion. We thought to have found intrenchments round this mount, and that the fable had reference to some Danish troop who kept the place as a station, from whence they could commit depredations on the country, and that the story of the hero imported some chief personage's victory over a public enemy: But there is not the least trace of any such matter, and the whole miraculous tale has no other evidence than the memories of old women. Our map makers have figured the place very significantly.