I think native English speaker who had never heard of Vaughan (sure we can find some of those) would likely to pronounce it like "Vog-un" - /ˈvɒɡən/ or "Vog-han" - /ˈvɑːɡən/
Maybe there's also an interesting thread to pull on in that the pattern may be more pronounced for names (e.g. Hughes). Just ruminating here though, I don't have a source for any of this.
Loughborough, which has it both ways. (Apocryphally pronounced by Australians as "Loogahbaroogah".)
How about Sequim, WA. Guess how to pronounciate that.
My years of french class steered me wrong there.