I was told quite emphatically that the speed limit on all lanes of motorways are 70mph unless signed otherwise on a visit to Leicester Motorway Control Centre, and I have never found anything to say otherwise. I also read in the Highway Code that it was OK to pass, on the left, slower moving traffic in an outer lane. Maybe a quick flash, from the nearside lane, to warn of his presence would be acceptable, possibly a toot of the horn if he thought the car driver was 'asleep'. So, yes, I would consider that the lorry driver was at least being aggressive. Not necessarily illegal, but definitely questionable of a driver hauling X amount of fuel.