>>38855521A theory I saw in another thread like 2 days ago said that it could be a reference to the Bisterne Dragon story, and from reading about it it does seem to fit given what we know so far, and could possibly fit with the leak about Eternatus the "evil legendary".
"The local tradition is that a dragon had his den at Burley Beacon, about 3 miles (4.8 km) east of Bisterne, at Burley. There are several versions of the tale, one being that the creature "flew" every morning to Bisterne, where it would be supplied with milk. In order to kill the dragon, a valiant knight (usually named Berkeley) built a hide, and with two dogs lay in wait. The creature came as usual one morning for its milk, and when the hut door was opened the dogs attacked it, and while thus engaged the knight took the dragon by surprise, the dogs dying in the affray. The dragon slayer himself, says another version of the tale, only succeeded by covering his armour with glass, and a popular telling of the story has it that the fight raged throughout the forest, with the dragon finally dying outside the village of Lyndhurst, his corpse turning into a hill (now known as Boltons Bench). Though the knight had defeated the dragon he had been mentally broken by the battle, and after thirty days and thirty nights he went back to Boltons Bench to die alone atop it, his yew-wood bow falling on the ground beside his body and eventually sprouting into the yew tree which can still be seen today."
