"Experienced" drivers lacking knowledge or rules of the road

What makes you think that he was an "experienced" driver.

Maybe he only passed his test last week.

I agree,though, that a lot of people have no clue in relation to negotiating a 3 exit( or more) roundabout

I only see one lane on that approach, not two?

The actual, real rules of the road, not the interpretation of them on the Aviva website which appears to be where you got your quoted text from, make no mention of forming extra lanes on the approach to roundabouts where there aren't any. What "everyone" does isn't important here.

Anyway, IMO what you did was bit of a dodgy thing to do on a small roundabout like that, and utterly pointless too. OK, on a much larger roundabout, with marked lanes on the entry, and marked lanes around the roundabout itself, yes, but not in this case.

40 years driving but never did a test i'd say. Loads of them around.

If it was his middle finger then that wasn't an indicator ;)

You were doing well till the second half of your post, left lane if marked on approach is left or straight on. If you use the right lane for going straight there are certain descriptions for your behaviour which can't be used here.

Apart from that given there were no lanes on the roundabout in question it would seem that the other driver was leaving room for cars which were turning left only. This was wrong, what he should have done was move to the left to allow cars that were turning right to move alongside instead.

Which car exited the roundabout first, yours or the other car?

It is obvious that people in general should do a rules of the road test when renewing a licence every 10 years.

However, those who design Irish roads should be tested too, some of the designs are well below par.

for instance, on roundabouts at dumbbell junctions on roundabouts, when you approach there are two half lanes, but there is no turning right, and so all traffic should use the left lane, unless doing a U turn. But there are no markings to contrary, what is that about?

I had a Barton’s Coach driver tell me this week that it was ok that he stopped his coach slap bang on a pedestrian crossing because “read the rules of the road, I had committed to the green light “.

The idea of not committing to a green light when there is clearly no room for him to clear the crossing never entered his tiny mind.

Professional driver, who presumably attends his mandatory CPC training every five years.

Dose.

Once! Once, in 1979, they cleared a backlog with an amnesty and 44 years on it's still spouted every time a driver over the age of 60 is mentioned.

These cars are positioned correctly to continue straight on.

Same roundabout entering from N52, two lanes clearly marked;

My reading of it; you undertook on the roundabout.

In the US I've seen signs such as Left Lane Must Turn Left.

Here we rely on road markings which can't be seen in traffic.

We've so fond of signs for overload of secondary information but not for something as important as this.

There's far too many badly designed and laid out roundabouts, coupled with dodgy driving, it's not a good combination.

If you examine the pictures (in @chooseusername's post above) of the approach to the roundabout, there is no left lane or right lane - there is only one lane. Squeezing up an imaginary lane to the left of a car already at the yield line and overtaking the other car on the left on the roundabout was not acting correctly.

The other car showed poor lane positioning but in the event of a collision the OP would have been in the wrong.

It may be practical and it may be the done thing but if you approached the roundabout in the right lane and took the second exit and collided with a car that had used the left lane you would be in the wrong. It's all all right until it isn't.

I frequently use a similar roundabout where there's often a tailback from the first exit but the local authority has taken traffic flow into consideration and clearly signposted, with advance signage and road markings all clearly stating lane priority altered ahead, left lane is for left turn only and right lane for second and subsequent exits.

If there's a problem with a junction layout a complaint should be made to the relevant authorities to have the junction layout altered, winging it and hoping for the best because it's what everyone else seems to be doing isn't going to fix anything and in the event of a collision the letter of the law is what counts.

The rules haven't changed. It's even highlighted on the first page inside the cover of the rules of the road, https://www.garda.ie/en/crime/traffic-matters/rules_of_the_road.pdf

There's just a lot of poor drivers around.