English spelling is in many respects not phonetic and there is often no one-to-one mapping between spelling and pronunication.
E.g. 'a' is /ej/ or /ey/ instead of /a/ as in Albert
'c' is /s/ not /c,ts/ like in Tsunami or Cyprián
'e' is /i/ (this is the most ridiculous, how can you pronounce as "i" when in most words it's E e.g. Edward, met, get, hemp?)
'i' is /aj,ay/ ? Am ay en aydiot?
So, the question is who can we thank?
I think it is not due to influence from French because their pronunciation is quite logical (well maybe except the weird 'e' that sounds like German 'ü' ;) )
http://www.youtube.com/watch?v=_LYy3P2okyw
Which language or people brought the 'e' that sounds like /i/ and 'i' that sounds like /ay/ to the "Inglish" language?