Earlier quoted context omitted.
>> In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road At night i was on an airport transfer bus heading down the Amalfi coast and the driver was flashing his headlights before barrelling into a hairpin turn giving no room for oncoming traffic. I stopped stamping on the imaginary brake pedal quite so hard when i realised this signal must mean I’m coming through which is th…
The highway code disagrees with you. Flashing your headlights or sounding the horn should only be used to draw someone's attention to the fact that you are there.
The actual uses of flashing headlights are much more varied than the official version. For example "you are driving with your headlights off and it's dark", "you are blinding me with your main beams" and "a tree has fallen in the road ahead". I would wager that the unofficial version outweighs the official 10 to 1.
The only danger with flashing someone to give way is when there is potential for it to cause a conflict with other vehicles, for example a cyclist on your left. For that reason I always check my mirrors and slow to allow someone to cross in front of me rather than flashing them. Most people figure it out but don't completely disengage their own perception.