I think Norman's background is deliberately sketchy - I'm less interested in his genesis than his impact. Blame my mentor at the time, one Harold Pinter, who directed me early on when I was playing Stanley in his deliberately opaque The Birthday Party. I too was mystified as to where my character had come from or even, after the play had ended, where on earth he went. So I asked him. Harold looked at me for a second and then gave me the immortal note, "Mind your own fucking business." I sort of knew what he meant and, after over 40 years of directing, it's one I rather wish I'd had the courage to give at times!
We recently finished a rewatch of the 1977 TV adaptation of The Norman Conquests by Alan Ayckbourn. The three plays make a great weekend of viewing for Friday, Saturday, and Sunday nights. We watch them every 5 or 6 years; the familiarity is there, but the details have been forgotten so there are always fun little surprises. The acting and comic timing is crystal-perfection.