Oldman, not old man

Another thing I watched over Christmas was a repeat of A Touch of Cloth, a comedy detective series by Charlie Brooker. There's a character in it called Detective Oldman, and many jokes are had around her surname and the phrase old man. The thing is, the name is pronounced differently from the phrase. You pronounce the name with a reduced second vowel, so it's [ˈɒldmən], whereas the phrase old man is pronounced something like [ɒldˈmæn] (the first vowel varies a bit). Even if you don't read IPA, you can see they're different in the vowels used and where the stress is placed. This meant that in the programme, for the jokes to work, her name had to be pronounced like the phrase rather than in the usual way, which sounds decidedly weird.