Information, instruction, training and supervisionE+W+S
21. In the case of a drilling, well intervention or workover operation to be carried out on a well—
(a)from an installation, the duty holder; and
(b)otherwise than from an installation, the well-operator,
shall ensure that the operation is not carried out, unless it is carried on in circumstances where the persons carrying out the operation have received such information, instruction and training, and are being so supervised, that the risk to health and safety from such operation is reduced to the lowest level that is reasonably practicable.