I looked up the details of the crash in which Hugh Cahoon was killed.
The JetRanger was G-BFJW of European Aviation and the crash was on 16 Dec 1996 at Parkway, Herefordshire, details as follows:
On take off in poor visibility, a/c drifted backwards from hover, main rotor struck tree & separated. A/c destroyed. 3 fatalities.
AAIB Field investigation: The helicopter was seen to climb in the hover to a height of about 20 ft. It then moved slowly backwards and upwards until one of the main rotor blades hit a tree. The force of this collision caused the rotor to detach itself and the helicopter was turned and thrown rearwards. The helicopter was flown in a controlled manner up to the time of the accident and the pilot had commenced a transition to forward flight by tilting the rotor disc forwards. Apparently, this was not done sufficiently to prevent the helicopter drifting backwards until it hit the trees. It was a dark night with considerable cloud cover and the lights of the adjacent house would at that time have been positioned below the helicopter and on the side away from the pilot and therefore out of his field of view. The effect of such a lack of visual clues would be to exacerbate the difficulty the pilot would have had in appreciating the rearward drift of the helicopter, possibly caused by the wind, in what was a very confined area. Safety Recommendation 97-22 made regarding minimum safety standards for corporate operators.