Used to take JPs to 35,000 ft unpressurised. ISTR Canberra at 40,000 ft pressurised to 26,000 ft equivalent. Don't recall anyone getting altitude sickness, though common mountaineering at lower levels. Can anyone explain.
The Canberra, in common with many, had a pressurisation schedule of half the altitude plus 2000. So at 45,000, the cabin alt was 24,500. Mild decompression can start at 18,000 and it was common to get "aching joints and shoulders" on long transits.