This was found on the northern slope of Ingleborough mountain in the Dales, N. Yorks, below the major landslip. It was probably lost whilst hunting, or maybe it was part of a weapon from the hill fort (earlier than Bronze Age) that used to lie on the summit of Ingleborough.
(later notes) Although I've supposed an eastern England origin for the flint, there's no proof that it originated from there. The patina/coloration of the arrowhead is consistent with an acid (peat) etched stony material. Flints found away from acid ground don't have this amber colour and the best and hardest of flints are found at Grime's Graves near Thetford (Norfolk) - the flint from there is black as charcoal when newly broken, but the outer patina is creamy white, probably from being in contact within the chalk it's usually embedded.
Maybe someone's investigated the chemistry of surface flint coloration?