I think there are a few issues.
My dad, despite being in his 80s is generally a good driver. I don't have a car at the moment so last time he visited he drove me to a local shop I wanted to go to.
We were on the ring road and my dad kept going in to the left lane, the left lanes all peel off so you have to be in the right hand lane to get round the ring road.
So sometimes an unfamiliar road layout can be to blame.
Foreign drivers. You can drive in the UK for a year on a foreign licence. There are designated countries that have agreements with the UK so that you can just exchange your licence for a British one.
One of the countries is Hong Kong. Someone I worked with had a Malaysian licence, now you can't exchange that licence for a UK one, but you can exchange it in Hong Kong to get a HK licence.
Then you can exchange the Hong Kong licence for a UK one.
I was in the back of a cab a while ago. I was giving the driver directions that included quite a narrow lane. There is just about enough width to pass and there are passing spaces. He panicked, I said stop the car and let the other driver past, so he pulled up on the right hand side.