© An ogival wing was chosen to give the best combination of lift, drag and stability characteristics at high Mach numbers.
© Fixed inlets for optimum performance at Mach 1.5-1.75 were chosen for simplicity.
© Some parts of the control system were based on those of the Hawker P.1127.
© One of the BAC 221's hydraulic systems was similar to that of the Bristol 188; the second was similar to that of the P.1127.
© Continuous voice transmission enabled the chase-plane to hear the 221 pilot.
© The blue finish was applied to make the woollen tufts stand out better on film.