Album five set me off to find out what the BA helicopters were used for, which lead me to "On 2 May 1984 a Boeing 234 (G-BISO) crashed in the East Shetland Basin of the North Sea, 8 miles (13 km) north west of the Cormorant Alpha Rig. All crew and passengers were rescued by other helicopters and boats. Although not damaged in the accident the helicopter sank after 85 minutes.[5] The aircraft was recovered for post accident investigation and later refurbished to fly again."
How times have changed... in many ways!