Paris didn't have a 4-runway airport in 1974. CDG had 2 runways for its first 24 years of operation.
Though of course, unlike Heathrow, it was designed from the outset with space earmarked for future expansion.
Yes, had forgotten that, but as you say, it
was in the plans. The penny should have dropped with the UK government (which ran Heathrow at the time)!