As a 'champagne rider' I had a trip up to the cockpit (remember those days?). I was interested in the IAS as we were doing M2.02 at the time at FL600. I fully expected the old girl to have a fairly low Vne but was surprised to see that it was redlined at 530kts. I was quite impressed.
Replies "I'm doing a cool thousand..."
"OK I'm passing you on the right..." and it did.
I had heard stories of the 'Thud' being brutally fast at low level when devoid of bombery appendages.