Interesting, I was going from what I remembered from IRRS journals as well, but clearly I misremembered
it was one of their articles that mentioned 118 once being recorded when the 071s were fairly new, but that it later transpired the mileposts in question weren't entirely accurate. It did go on to say that those high speeds were pretty common before the 90mph limit was instituted - though I do accept that the 75mph linespeed did make it somewhat moot.
The article in question was in the early 2000s but I can't remember exactly which one it was now....
Thank you for posting it though - that was a fascinating read. My membership had lapsed when journal 200 appeared (though I am a member again now), I'll have to see if I can obtain a back issue somehow....