Tony K,
Similar grip here in Australia from Hawker Australian Demon, numbered 931/35, which I understand is serial 931, production date 1935.
All ‘Hawker’ Hectors were made by Westlands, so if there is a HA or HE (Hawkers) inspection stamp on any of the components below the BSA grip it is not Hector.

All Hinds and Hectors only had one gun, one trigger connected via cable to CC gun gear. Two trigger grips sometimes had a rubber ‘boot’ fitted over one trigger.
At this stage, I am unaware of ‘modern’ gun cameras, linked to CC gear, being fitted to Hart biplanes, requiring trigger actuation.
I understand that manually operated gun cameras, actuated by pulling a trigger in the usual grouse shooting way, were in operation.

All original Hart biplanes had Palmer brakes, pneumatic or hydraulic, rudder pedal assembly actuated.
Using a hand trigger as pneumatic valve controller, as per a WW2 aircraft, implies the fitting of Spitfire-Mosquito differential braking valve to a rudder pedal assembly unit, which I do not think is fitted to Hart type biplanes flying at Shuttleworth, but I live to learn.

Does the Air Corps Museum have a Dagger engine, by the way…