Peter is a serial offender at getting his AM and PM mixed up. As his country uses a twenty four hour clock system, we should forgive him.
How do you go with a twenty four clock? I am not bad with it as I have to use one at work. Still, even at work, probably to other's annoyance, I write in am and pm unless there is no other option. My workplace is quite perverse in that if I worked until 2 am, I would be working until 26.00.
At home we always set clocks to am/pm where we can. I can't see a twenty four clock ever catching on here, not when we use a twelve hour clock face. How can you visualise the time in the twenty four hour format with a twelve hour clock face? You can, but it requires thought. In the twenty first century, I think we are already overloading our brains and memory.