I have since had a reply from the UK Health & Safety people. They say that 10' high or 4 stack layers is normally OK but that in good conditions (presumably beer kegs on good pallets would qualify?) 6 high can be permitted.
Surprisingly an factory equipment suppliers catalogue shows the depot in question with 7 high stacking at around 20+ feet high!
I have suggested they take a look as 8 high is now normal there. In the picture they show a local delivery truck at around 12 feet high and the beer is clearly 10 over the truck roof height - the roof will be translucent fibreglass or thin aluminium sheeting!
I have asked about the bouncing capabilities of beer kegs from height as I believe they will rebound high enough to enter the cab area of a fork truck or can ricochet off the counterweight across the yard - perhaps even taking the gas tank as they go!!!
Any further comments would be most welcome.
Best wishes, Rod

I Canada we only stack freestanding to 4 metres, if higher we use racking.
How high to stack is decided by safety first, and productivity second. If product is falling from the stack the root cause is improper stacking or operator error.
Don't worry, I am sure litigation will eventually catch up and solve the problem after so many people have lost their lives and the companies are deemed negligent to safety laws.