Spotter alert!
The later RAF versions of the series 3, the HAR 10 also had the Bristol Siddeley Gnome 101, 1050 shp but de-rated I seem to remember.
I got the bug for rotary flying after a spell as a Whirlwind passenger/professional survivor whilst holding at RAF Leconfield. I later trained on them as pilot, rather underpowered but quite a docile old beast (the aircraft, not me!); basic students were required to do solo engine-off landings at around the 70 hour stage.
They got something of a reputation for tail rotor drive failures once retired from active service and sold on to the civvy market.