Good grief, shoot the Corsa driver seems to be a popular knee jerk reaction.
To be fair to the Corsa driver, they've been driving down a one way road, that then merges with another lane, which if there's vehicles coming down it or the road it splits to, it would be obvious wasn't the same direction as yours, but if there wasn't any other traffic?. The only other indication that the other lane is opposing are arrows on the road, obvious but there was also rain on the day in question. It isn't impossible for a Sat Nav to send you a confusing way. Just before getting to that bit, if they were using a Sat Nav it would have been telling them to keep in the right lane. There is evidently a sign missing just before the road splits to the slip road, is this meant to be a sign saying "Death awaits those who drive down here!"?
Maybe they had an aggressive driver sitting on their rear bumper distracting the hell out of them? They are in a Corsa after all and were likely holding someone up as the dual carriageway became a single lane.
Just saying, Angles and all that. Easy to write off as stupid Corsa owner/woman, especially on an internet forum. Look at it a little closer though and there seems to be some mitigating circumstances apparent or possible.