Hmmmm! I think people need to take other elements into this discussion.
When the first motorway was built in the 1950s (I think), I don't think they took into consideration the growth of the amount of vehicles there will be on the road. Hence the motorways weren't designed for the modern volume of traffic. We need to take into consideration the initial traffic compared to now? How much and the distanced travelled by people commuting to work compared to now? The amount of haulage upon the roads at any one time?
I think just the fact that there are more cars more often on the roads means that the 1st lane cannot accommodate the traffic alone so the 2nd lane has now to be used.
In countries like America and China they are more aware of the traffic burden and have built larger 'super highways'
Just my thoughts, again not defending middle lane hoggers. 
Let the abuse begin. 
....No, you are right about the original motorways. Also the UK rarely spends enough money on transport infrastructures with a longer term future in mind, unlike the French for example. However, in my opinion, middle lane hogging is only acceptable when the inside lane is not free enough of traffic to allow SAFE swopping of lanes as you make progress overtaking.
It's not safe to cause others to brake while you cut in and out just to grab the inside lane. You should always use the inside lane when you consider it safe to do so. However, when I see a junction with slip roads, unless there's a huge area of visibility, I usually swop lanes to leave the inside lane free for those vehicles joining from the slip road.
Isn't all this common sense?
