Never really understood undertaking?

So about a few days ago while driving along the busy motorway, an unmarked police car signaled me to stop on the hard shoulder. When the police officer spoke to me, it was because I undertook 2 vehicles that were on the middle and far right lane and I used the far left lane to undertake them. I was travelling on a standard three lane motorway. At that stretch where I was travelling, the left lane does not lead to an exit in which I know in some stretches, you need to be on the left lane to use an exit.

I undertook them because one was completely hogging the middle and the other on the far right lane. Those two cars were beside each other for a long time doing like around 60mph or something there and it dind't seem like the vehicle on the far right lane wasn't going much faster as the vehicle in the middle lane. The far left lane was clear. They were no vulnerable speed limits around where I was travelling. They were no signs telling left lane drivers to move to the middle lane. I was travelling in the middle lane hoping the car in front would move to the left. Apparently, the driver did not so I decided to just go the left lane and just undertook the 2 vehicles still within the speed limit at 70mph and a few seconds later, an unmarked police car behind me signaled me to stop.

I argued saying the 2 vehicles were completely hogging the middle and right lane at 60mph and asked why he didn't stop either of those drivers instead of me. I thought hogging the middle and far right lane would be more serious. The police just sticked with the fact that I shouldn't undertake. Eventually, the police just let me off with a warning and be more careful.

I have never exactly understood why undertaking is dangerous. If I was sticking behind those 2 vehicles on the far left lane not undertaking them at 60mph, we would have been causing slow traffic along the motorway.

I have encountered so many middle and far right lane hoggers on the motorway. If both the middle and right lane are being blocked and the left lane ahead is clear, I feel like it makes more sense to move to the left instead of causing a road rage with them, causing slow traffic behind and carefully undertake them at the appropriate speed.

I know you are allowed to undertake on certain circumstances in which I thought that was my case.

My questions are:
Was my undertaking considered dangerous or appropriate?

What would you have done if you were in my situation travelling along the motorway? If they were vehicles hogging the middle and far right lane beside each other at around 60mph and you notice the left lane is clear, what would you do?

Is undertaking still dangerous up to this date? I seem to have mixed answers when I asked my friends and families about this. So just wondering what you guys think?

Let me know your answers below. Thank you

The person on your right could come back into the left lane at any time

The person on your right could come back into the left lane at any time

Never really understood this either. Why would you move left without proper observations? If somebody were to hit you in this manner it would still be their fault surely?

I don't know if they bother to enforce it.

This is why I hate middle lane hoggers.

You shouldn't undertake; the people in the middle lane could move left at any time and because they aren't expecting you to be there they could hit you.

It's irritating, I know. I'd argue that a friendly flash of the lights to prompt a driver to rethink their lane positioning would be a good start. If they continue to obstruct, perhaps make you're irritation a little more clear.

Unfortunately there is no approved way to handle this other than to sit and let the pricks obstruct you, but it's strongly advised you do not undertake.

On empty motorways when there's some pillock hogging the middle lane in the middle of the night, I'll make a point of crossing the entire motorway from Lane 1 to Lane 3, overtaking the moron, and returning right back to Lane 1. They seem to get the message sometimes. I appreciate this doesn't help in the scenario you described, though.

you should have been more patient.

the boys in blue would have deal with the middle lane hogger. And you would not have to stop on the hard shoulder for a ticking off.

just take it as an experience.

Actually those 2 cars were literary driving beside each other for almost 5 minutes and i was behind the middle driver for around that time lol. I'm pretty not only just me but other drivers would have gotten a bit impatient to wait for the middle lane car to move to the left. Even a few drivers undertook us before I decided to undertake.

As I said, it's irritating, I'm well aware of that. It is however deemed dangerous to undertake, more so than to hog the middle lane.

We have a lot of drivers out there on the roads that are simply incapable of proper lane discipline, and that's not your fault

You can legally undertake a vehicle if you then don't instantly pull in front of them. For example if someone is hogging the middle lane and no vehicles for a fair distance in front in any lanes you can undertake them in the slow lane as long as you stay in the lane and don't move into the middle lane straight away to overtake a car in the slow lane. Maybe a couple of minutes after passing them or a mile after passing them it should be fine.

I do it and occasionally the middle lane hogger will realise after I have passed them in the slow lane and they will move over into the slow lane. Any middle lane hoggers should be fined under the new law however I don't know if they bother to enforce it.