It was myself that originally devised the Castleton Classic 200k route. Before it became an Audax event it was the North Birmingham CTC's annual 140 in 12 with a slightly different start and finish point. That was around 1982 if I remember correctly and it became an Audax around 1995.
Andy Wilkinson and Lynn Taylor rode it on a tandem as training for their upcoming end-to-end record in 1995(?) and finished in just over 7-hours I think.
I do know that Mick Potts rode and completed it in under 8 hours.
Having known Mick, I can imagine him dryly commenting “ if I knew it was timed I’d have made an effort”
Seriously though, Audax cannot, and should not, time individuals or publish times. To do so would make the event a race within the Cycle Racing on the Highway definition, and would also change the whole character and ethos of Audax.
I can’t begin to imagine the work in organising a 200km race, for of course a much reduced field; probably 60 maximum. Police permissions, risk assessments, accredited marshalls at every junction etc etc.