The Armstrong Siddeley Stentor was the powerplant of theBlue Steel stand-off missile that entered service with the V-force in 1961.
Stentor was a HTP/Kerosene-fueled two-chamber motor. The different sized chambers were required to provide a boost phase (large chamber) followed by a cruise phase with the smaller chamber. The example in the photo is on display at Cosford.
Rocket Engines or Guided Missiles