"Rafe" is simply the correct pronunciation of Ralph.
Bertie would be short for Albert, that's not a hugely ordinary name these days
My point is, if you were actually 'posh' (whatever that is) you wouldn't christen your child "Bertie" - you'd give the long proper name, Albert (or Herbert, but that is shudder-making). I don't know about Albert being ordinary or not - to me, it sounds quite an old-fashioned name, and always reminds me of a chauffeur my grandmother had (whose name was Albert, never Bertie!).
And that's the main thing, isn't it? That names have associations for people, and they'll be different associations for different people.
I suspect I'm what most MNetters would call 'posh' but in my family we use simple classic English names, from a pool that goes back a few hundred years - all the men are called names such as James, Thomas, George, Patrick John etc (with one middle name that is common to all the men in my extended family back a couple of hundred years). All the women are names such as Elizabeth, Sarah, Katherine, Victoria etc - again with a frequently shared middle name. We don't do it deliberately - it's just our particular family culture.