Plus, there is a difference between a private car driver going at 80, and a public coach driver going at 80. Which is why the "slow" lanes of motorways are populated with coaches and lorries. Their livelihood depends on them sticking to the rules on speeding, plus they are responsible for more than their own life when driving. So they don't speed. I am sure an HGV or coach driver wouldn't be the best around Silverstone, but boring, defensive driving = safe driving