A mangling by me. The original quote, by Stephen Frears about Daniel Day-Lewis, was:
Interviewer: ‘Can I get a quote about Daniel?’
Frears: ‘I used to know him before he was Irish . . .’
(Day-Lewis’s add-on: ‘I never knew Frears before he was a facetious slob.’)
In my head, the way my version of that line has been:
“I’ve known Daniel so long, I can remember when he was English…”
…which only goes to show you my capacity to elaborate.
These days, I tend to use the form to draw similar contrasts, though.
“I’ve known Jerry Pournelle so long, I can remember when he was a patriot.”