In terms of 37s still on the mainline, then these are the fleet lists (to my knowledge anyway!)
DRS:
37038, 37059, 37069, 37194, 37218, 37259
37401, 37402, 37405, 37409,37419, 37422, 37423, 37425
37667, 37682, 37688
37601, 37602 ,37603, 37604, 37605, 37606, 37607, 37608, 37609, 37610, 37611, 37612
37703, 37713, 37716, 37718
DRS still own a lot of locos now stripped for spares, such as 261, 510 and a couple of others.
37703 is to be swapped with 37401 as 703 had a shunting accident at Daventry and has bent frames.
Network Rail:
97301, 97302, 97303, 97304
WCRC:
37516, 37518
37669, 37676, 37685
37706, 37712