Alphabites Does It Really Work Or Not?
How it Works3 mins ago
No best answer has yet been selected by keitra. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.I'm not sure, though, about its referring specifically to the centre pages, even in the early days. In fact, one of the illustrative quotes in the OED mentions "a four-page spread", which presumably wouldn't work according to your description.
There has, though - as you say - since the 1940s at least, been something specifically referred to as a "centre spread". 'Spread' itself has meant an extended article since almost a century earlier than that. All-in-all, in modern usage, it doesn't seem to matter much whereabouts in the publication it appears. Cheers