Nipped out for some milk earlier this AM, (remember that 'AM', you'll need it later)
and spotted this notice in the Post Office window.
The USP of the 24 Hour clock is that it avoids ambiguity.
4.50, unless qualified by AM or PM can be in the morning or the afternoon.
1650 can only be in the afternoon, but you knew that, didn't you?
So why 1650PM?
I didn't notice the entry for Saturday until I downloaded the pic.
12.15AM. That's 0015, isn't it?