I have had a car licence for 20 years which at 1 point included a PCV ( Bus Category D ) between 2006 & 2008 and therefore I can say that having driven s big vehicle myself ( although not a lorry ) that the driver should have known better than to pull out, especially as most lorries have double the number of gears as most cars dop 10 or 12 gears compared to 5 or 6 in cars.
The buses I drove had 3 grared Voith automatic gearboxes and were relatively quick to get going, however, 1st gear on a lorry is a much lower ratio than 1st gear on a car or bus, that is why if you are behond a lorry / truck you will often hear about 5, 6 or even 7 gear changes before they gave reached 30 or 40 mph.
Also if I may, I would like to add the advice that to anybody who does encounter this situation as described in post #1, if you can do so at the time, follow this procedure :
1, Note the vehicle registration
2, The time and place where the incident occurred
3, Any company details off the vehicle ( often available off the cabside of the towing unit )
4, Ring the company to which the vehicle belongs and report the incident as calmly as possible including all the above details in points 1 & 2 and give a full description of what happened.
After this procedure, you can be safe in the knowledge that you have played your part in getting a driver who would rather use rudeness and hand gestures instead of waiting his turn, off the road.
I often had cars pull out in front of my bus, notably at peak travel times 16:00 - 18:30 here in the wirral and I can tell you from my experience that blowing your horn or flashing your headlights is of no interest to drivers who pull out in front of you.
The number of 2 fingered gestures or other signs which are too X rated to mention on here was absolutely unbelievable.