Co-operation and co-ordination
22.—(1) Where two or more responsible persons share, or have duties in respect of, premises (whether on a temporary or a permanent basis) each such person must—
(a)co-operate with the other responsible person concerned so far as is necessary to enable them to comply with the requirements and prohibitions imposed on them by or under this Order;
(b)(taking into account the nature of his activities) take all reasonable steps to co-ordinate the measures he takes to comply with the requirements and prohibitions imposed on him by or under this Order with the measures the other responsible persons are taking to comply with the requirements and prohibitions imposed on them by or under this Order; and
(c)take all reasonable steps to inform the other responsible persons concerned of the risks to relevant persons arising out of or in connection with the conduct by him of his undertaking.
(2) Where two or more responsible persons share premises (whether on a temporary or a permanent basis) where an explosive atmosphere may occur, the responsible person who has overall responsibility for the premises must co-ordinate the implementation of all the measures required by this Part to be taken to protect relevant persons from any risk from the explosive atmosphere.
What the Enforcement Guidance says: