Now I've checked it doesn't seem either of the Dragonflys were operated by Bristow.
G-ANAL ( later G-ANZL ) was registered to the Evening Standard in June 1953 and maintained at Blackbushe by Silver City. It was re registered in March 55 which helps date the photo.
G-AOAJ was built in April 55 ,retained by Westland for their training school and written off in October 56.