I believe they do but Bristow International do not operate in Nigeria as far as I am aware. Maybe they have won a Bell 407 contract elsewhere else? Bristow USA sold off their single engine fleet to Rotorcraft Leasing some time ago to concentrate on deep water operations.
if I understand well, IBU is Monthy Phyton Flying Circus
Far from it. IBU is a very professional organisation with some excellent people who try to do things properly - even in places where that is difficult.