VC10 had a speedbrake limit of 345KIAS.
During the high IAS run on Full Flight Tests, we increased speed to 350KIAS, checked the speed warning horns, flying controls and TPI, then checked that speedbrakes could not be selected - the lever was held in. Whilst maintaining pressure on the speedbrake lever, speed was reduced to 345KIAS to check that the speedbrakes would then extend to the normal baulk limit.
Didn't the Lightning also have an airbrake limit?
Trim changes in some aircraft were quite significant. Descending the Vulcan you were supposed to select mid-drag airbrake, allow the nose to pitch down (took about 7 seconds), then idle thrust and finally high-drag when stabilised in the descent........
As a youngster, I thought I knew better. So selected high drag, closed the throttles and then started to dive off the height against drag to achieve a higher descent rate than with the normal technique......and then the trim change suddenly made its presence known and the dive (from FL450) became rather steeper than anticipated, rapidly reaching M0.95+. At such speeds, considerable elevon is automatically applied by the auto mach trimmer, so there isn't much left for pitch control until the IAS increases in denser air lower down. Which it did.
Nearly dropped a HUGE sonic boom - over HQ 1 Gp RAF Bawtry, coincidentally!
Since then I've flown as the QFIs taught, rather than trying something else!