BHAB job
MaxNg,
You're right. BHAB is the entity responsible for checking that helideck is safe and personnel properly trained on any installation/vessel in UK waters, before helicopter operations are carried out.
In fact, according to the ANO (and JAR-OPS 3 these days) you as the commander are responsible to check the conditions of any landing site other than a licensed aerodrome you intend to use, but since this is not practicable to do in our type of operations, you discharge that responsibility on BHAB.
The fact that this incident happened simply shows that BHAB inspection regime failed somehow. Surely your SAR will end up on a BHAB desk!