Hammer, I am fully aware of why it happens, I have been driving on motorways for over forty years.
The situation you outline is ideal - but unrealistic as we both know. There is far too much traffic on any motorway to simply use the inside lane and move in and out. As I explained in my post, to move in and out of the left lane to pass the heavy volume of traffic in that lane, in driving rain, at night, would have presented more dangers than it avoided, so i stand by my decision to remain in the middle lane until a reasonable length of clear road occured in the inside lane, which simply did not ocur.
Regardless of that, the rules on overtaking are clear - you overtake on the right of the car you wish to pass, you do not cut across another driver in order to undertake a vehicle which you decide is not going fast enough in the overtaking lane.
Yes, in an ideal word, we would all drive as we should, but I was driving safely for the conditions, I was cut up by a maniac who did not check his mirrors, and I was forced into avasive action without time to either check or signal as thorougly as I would have liked.
In an ideal world, such drivers would be banned for life, but we have to deal with the motorways as they are, not how we would like them to be, or indeed how they were when I first drove on them.