I obviously can’t comment on your drivers, but my experience of the use of those lights has always been illegal. The rules say you shouldn’t cause any unnecessary glare from your lights to other road users and recommend if you are being dazzled to slow down and watch the road on your nearside until the other vehicle passes.
Nowhere does it say a retaliatory flash is the correct or acceptable behaviour.
The RTA C&U regs also says that only white or orange lights may be displayed at the front of a vehicle. There is also a limit to how far from the road surface a light me be fitted and used. (I think its 1mtr from memory but stand to be corrected.) its certainly not above roof level.
Wherever these vehicles may end up, while they are using the UK roads they are subject to our laws.
My point, and thus my question to you, was if a driver, (from a company other than yours of course), caused an accident by use of those lights and was convicted of dangerous driving as a result, his company would be liable under corporate liability laws. That could lead to substantial claims for damages against his company and if a death was to result from that driver’s actions, it could run into £Millions and even be the cause of that company having to close down.
Even in a case where the driver was issued with a FPTor order for misuse of the lights and directed to remove them, the company would be liable for the driver’s actions.
In the real world we all know why they are there and I am sure there are others on here that have had the instant suntan from these Knights of the road.
It’s notable that high profile companies like Stobbarts don’t allow these adornments on their vehicles.