Two points only:
JMHO "since 1970" needs the phrase "if not before".
Also JMHO, if there's any way to bend an asset to the benefit of a derp, that asset's gonna get bent. Sometimes before it's actually employed as designed.
(Don't tell me BH/WH, show me what the [BLEEP] did.)
That’s why I said “at least” since 1970.
My sources did not tell me since when. I had the impression, that it had been for years already in 1970. But I was not told that.