Aggressive driving by the lorry driver. Wanted to keep his momentum and felt inconvenienced therefore took his attitude out on other road users.
A professional driver should know better, sure it's inconvenient but so it someone losing a family member because someone was driving on someone else's time and doesn't care about other road users.
Same goes for the other driver though, right up the back of the car leaving the carriageway, deserved to be in an accident for that and his brake check. But the lorry driver should have seen this and driven accordingly. Day gets a lot longer when you have to mop up the scene of an accident.
Thisexact behaviour has cost many lives on a local A road, so easily done. As I've got older ive started to hang back and plod along rather than get bothered about slower or poor drivers. I make progress as fast as conditions allow, no point having a chip on your shoulder because someone else is not driving how you want them, just asking for a day in court and a tragedy engrained in your mind.