But these are not scenarios that are being discussed. We are talking about undertaking (or passing on the inside if you prefer) which is potentially dangerous and almost certainly avoidable with a bit of patience.
I was responding to your statement above when you said
"If you feel that you have to blast your horn and flash your lights as a warning when you carry out a manoeuvre then you are doing something risky that should probably be avoided if at all possible."
which covers pretty much any instance of using audible/visible warnings .
They would be likely to be seen as aggressive and provocative. If I saw someone sitting in the middle lane I'd think "What a ****". If I then saw someone undertaking them with horn blaring and lights flashing I'd think "And there's another one." I would give both an equally wide berth.
That might well be the case , but it is perfectly possible , and actually normal , to give advance warning of your approach without BLARING the horn and a single or double flash of the headlamps is in no way aggressive ( it is taught in response driving and also quite normal on continental roads , the problem is with the mindset of some UK drivers who take exception to it , despite it furthermore being taught in basic driving instruction and even being in the Highway Code ) . Whether passing on the left or on the right , the same warnings should be considered as appropriate .
As for the bit I highlighted above - I tend not to bother being judgemental about other drivers these days ; it is much easier and less stressful just to let them get on with their day and get on with yours without getting upset at them .
But those circumstances do not include undertaking because you lost patience with another driver's poor lane discipline and allowed that to compromise your own driving.
Again , just choosing to continue past a slower driver who chooses to drive in a lane further to the right does not infer any annoyance , impatience or aggression ; it is simply a more efficient way to drive : I quite often find myself driving along the nearside lane of the M8 or M74 , being in no particular hurry and able to make satisfactory progress there , perhaps sitting at 50 or 60 .
It is not unusual to find other drivers staying in lanes two or three at lower speeds than I am travelling at , my options therefore are -
1) to slow to their speed and remain behind them ,
2) in the case of lane two dwellers to move over two lanes , pass them in lane three ( perhaps having to take account of significantly faster traffic in that lane ) then return to lane one , or
3) just to carry on in lane one and pass them on the left ( I don't often give horn warnings or headlamp flashes , but just on occasion I might for whatever reason ) .
With lane three dwellers , option 2 does not exist but you do have an empty lane between you and then ; with the lane two dwellers you would normally have the option of using the hard shoulder to avoid them if they suddenly decide to move over .
A lot of people do not bother to use lane one of the sections of motorway I travel on my commute because it becomes an exit lane at various points with only the two right hand lanes continuing - yet these people will sit in lane two five miles before lane one closes !
