Bill Who!

Walking through the factory this morning, I saw a familiar shape coming towards me. Or at least, vaguely familiar. Having just come from the darkness outside to a brightly lit factory I was experiencing that mistiness which affects me now. S'like walking in fog until my eyes adjust to the change in light, and that can take 10 minutes or more.
Anyway, a vague figure.
"Morning, Bill!" I said.
"Who?"
Blast, it's Paul, who I've worked with for over twenty years. How embarrassing.
"Did you think I was Bill the labourer or summat?"
Yes. Even though he's taller than you, has got darker hair and just looks nothing like you, I though you were Bill the labourer.
"Of course not." I said, thinking fast. "I meant Bill Gates."
As I was walking away, it occurred to me that this was a tad unlikely. I mean, Bill sodding Gates!
My eyes, it seems, aren't the only defective part of my anatomy.