The Hawker Siddeley P.1154 was a planned supersonic vertical/short take-off and landing (V/STOL) fighter aircraft designed by Hawker Siddeley Aviation (HSA). Developed alongside the subsonic and smaller Hawker Siddeley P.1127/Kestrel, the P.1154 was derived from the P.1150. The P.1150 proposal did not meet NATO Basic Military Requirement 3 and, consequently, the P.1154 was born. This Mach 2-capable platform retained plenum chamber burning previously designed for the P.1150.