I've never met anyone called Magdalene but I would pronounce it with the "g" (and I'm in England). My assumption was that only the colleges use the antiquated pronunciation Maudlyn, but I could be wrong.
ReDemi - I seem to remember that when Demi Moore first became well known here in the early 90's I always heard her name pronounced as Demmy. Now, I tend to hear people call her Deh-MEE Moore although many people still pronounce it Demmy. I think it was just a wrong assumption (possibly people thought it should sound like "semi") and it spread. The name Demi (prn Demmy) has recently become reasonably trendy, possibly because it was used in the soap opera EastEnders. I see it hyphenated occasionally too e.g. Demi-Lee. Sorry, going off topic now.