"The model celebrates 80years of continuous production this year"

Can someone please explain this statement to me;
My understanding is that the 4/4 Series 1 finished production in 1951[?] following the introduction of the +4, the 4/4 Series 2 was introduced as a stable mate to the +4 in 1956[?].

Continuous production, my ****, next you'll be telling me that they don't have wooden chassis.