4.—(1) For the purposes of these Regulations—
(a)subject to paragraph (2), the operator of a container or vehicle shall be—
(i)the person who, having a place of business in Great Britain, has the management of the container or vehicle for the time being; or
(ii)if no person satisfies the requirements of head (i) above, the driver of the vehicle or, in the case of a container, the driver of the vehicle on which the container is carried;
(b)the operator of a tank, other than the carrying tank of a road tanker, shall be—
(i)the person who, having a place of business in Great Britain, owns that tank,
(ii)if no person satisfies the requirements of head (i) above, the person who, having a place of business in Great Britain, acts as agent for the owner of that tank,
(iii)if no person satisfies the requirements of either head (i) or (ii) above, the person who, having a place of business in Great Britain, has the management of that tank for the time being, or
(iv)if no person satisfies the requirements of heads (i), (ii) or (iii) above, the driver of the vehicle on which the tank is carried.
(2) Notwithstanding paragraph (1)(a), a person shall not be regarded as the operator of a container or vehicle solely because—
(a)he has the management thereof during loading or unloading; or
(b)the container or vehicle is on premises which are under his control.
(3) For the purposes of these Regulations, a person to whom a tank, other than the carrying tank of a road tanker, is leased or hired shall be deemed to be the owner of that tank, unless the lessor or, as the case may be, the hirer has made an agreement in writing with the person to whom he has leased or hired the tank to the effect that the lessor or hirer shall assume the responsibilities of the owner imposed by or under these Regulations.