Old English feawe (plural; contracted to fea) "not many, a small number; seldom, even a little," from Proto-Germanic *fawaz (source also of Old Saxon fa, Old Frisian fe, Old High German fao, Old Norse far, Danish faa), from PIE root *pau- (1) "few, little."
Always plural in Old English, according to OED "on the analogy of the adverbial fela," meaning "many." Phrase few and far between attested from 1660s. Unusual ironic use in quite a few "many" (1854), earlier a good few (1803).
There is likewise another dialectical use of the word few among them [i.e. "the Northern Counties"], seemingly tending to its total overthrow; for they are bold enough to say—"a good few," meaning a good many. [Samuel Pegge, "Anecdotes of the English Language," London, 1803]
"a small number of persons" (distinguished from the many), c. 1300, fewe, from few (adj.).
Never in the field of human conflict was so much owed by so many to so few. [Winston Churchill, 1940]