No problem mate.... I forgot to mention further that the failure on the Audi wasn't the roof rack, the brackets or the securing straps, it was the actual car guttering.
Both near side front and rear brackets had ripped through the gutters despite it being secured on firmly with an Audi OE roof rack fitted by Qualified technicians the day before with correct tensile bolts.
In hind sight... It is really sickening to imagine that something so light at no more than 20kg can do so much damage. One of the witnesses described it as:
"Like a missile being launched rearwards"
I did follow up a few weeks later with the Audi driver.... Just to let him know personally the findings of the examination, he hadn't driven since then. It was upsetting to actually think he was blaming himself and felt he could have done something better... It was just one of those things that a person can take every precaution but can't foresee or factor in random things like wind.
During my time with VOSA I have attended many incidents involving loads secured on roof bars, this was by far the worst.
Experience has taught me that there is NO completely safe way to carry a load just some offer a lesser risk than others.
Statistics showed us that trailer loads that are secured properly offer much less risk than roof loads due to the nature that a driver is far more aware while towing, slower, gentle on the controls and combined with changeable weather conditions, offers less chance of flying debris because of the height factor difference. So in turn, with gravity, debris tends to fall quicker in a shorter distance.
Just stay safe mate, it's all you can do.