The Min Connection for [stn]DBY[/stn] is 10 minutes - so making sure your trains are timed at least 10 mins apart** (may be slightly different for 9 mins*) you will be covered should you train into Derby be late.
** From when your train is timed into Derby to when the Connection is timed to depart.
* As you have not allowed the min connection time between your trains.
(But thats no guarantee the above is correct!)
I'm currently looking at AP prices from Mansfield or Nottingham to Blackpool North for later this summer. I notice, however, that for the journey which would be most convenient for me, the train that I would be booked on with this ticket from Nottingham arrives in Derby at 1033 and the connection to Crewe leaves Derby at 1040. Now that is only allowing 7 miniutes!
I know that if I booked this as an AP ticket (which would include a reservation from Nottingham to Derby with XC) and kept the printout of the journey details there should be no problems if I missed the connection but I would need some confirmation of my earlier delay for when I arrive one hour late at destinations later in my journey.
However, why is an AP Ticket being sold that only allows 7 minutes at Derby?
There is one AP journey from Mansfield to Blackpool that I was considering, as I don't need to get to Blackpool particularly quickly at only £7.00 but this uses a very unusual roundabout route! You can get this on the East Coast site by entering via Wilmslow.
Mansfield-Nottingham, Nottingham-Derby, Derby-Crewe, Crewe-Manchester Picc, Manchester Picc-Preston, Preston-Blackpool North.
This AP Ticket only allows 7 minutes at Derby, and although I would have reserved seats on many of the trains, there would be alot of explaining further on during my journey if I missed that connection and got delayed.