Cheers Chris, looks like we both may have won technically, so far! I haven't been to Derby for nearly 10 years and remember walking over a bridge to get to platforms. My friend reckons it is all underground when she was there a few years ago. Anyone know the station well these days for a definite answer?
"Derby station today has six platforms (all but Platform 5 are through platforms), connected by a footbridge, used as an exit to Pride Park and a new car park."
the over pass is for passengers to access the platforms
the underpass I believe is for the post office use for the mail trains that passed thru, it is said that this underpass also goes to the main sorting office