Richard Wordingham wrote:
> 'wolf' derives from Old English _wulf_. The 'o' is orthographic - I
> presume *uuulf would have been unreadably ambiguous in some hands.
And this despite the fact that we would in principle expect a lowered
vowel in a Germanic a-stem (cf. German Wolf, whose <o> is NOT
orthographic). However, the pre-Old English lowering of *u to [o] before
a syllable containing *a (originally allophonic) was somewhat
inconsistent. Perhaps the same or similar phonetic factors that
prevented the lowering of [U] in some Early Modern English words are
responsible for the failure of the OE lowering.
Piotr