Just a quick question, why do VT own their thunderbird locomotives rather than hire them in like EC do with 67s and GA do with 47s? If I was VT I would just flog all the 57s to DRS then hire them as and when they are needed.
They don't - they're hired from Porterbrook. They are a staple of the fleet - VT crew sign and operate them in normal service ie weekend drags and midweek night depot swaps. This allows much quicker response times to any incident.
EC et al have to ring DBS, find a man who can drive 67s and the route, and then communicate with one extra party.
I would think VTs arrangement is more beneficial to incident recovery times and procedure, if not economic efficiency.