Peak Rail currently operate their service with a steam loco on the Matlock end of the set and a diesel on the Rowsley end of the set.
The steam loco is currently 3883 Lord Phil.
The diesel is a choice of either 31270 or D8
Update 2nd April 2013
Due to D8 being out of service for repairs 31270 is the only diesel Peak Rail have to use as the T&T loco and will be used indefinitely until D8 is released back to traffic.