(1)For the purposes of this Part and section 1 of the Equal Pay Act 1970 (" the relevant purposes "), employment is to be regarded as being at an establishment in Great Britain unless the employee does his work wholly or mainly outside Great Britain.
(2)Subsection (1) does not apply to—
(a)employment on board a ship registered at a port of registry in Great Britain, or
(b)employment on aircraft or hovercraft registered in the United Kingdom and operated by a person who has his principal place of business, or is ordinarily resident, in Great Britain;
but for the relevant purposes such employment is to be regarded as being at an establishment in Great Britain unless the employee does his work wholly outside Great Britain.
(3)In the case of employment on board a ship registered at a port of registry in Great Britain (except where the employee does his work wholly outside Great Britain, and outside any area added under subsection (5)) the ship shall for the relevant purposes be deemed to be the establishment.
(4)Where work is not done at an establishment it shall be treated for the relevant purposes as done at the establishment from which it is done or (where it is not done from any establishment) at the establishment with which it has the closest connection.
(5)In relation to employment concerned with exploration of the sea bed or subsoil or the exploitation of their natural resources, Her Majesty may by Order in Council provide that subsections (1) and (2) shall each have effect as if the last reference to Great Britain included any area for the time being designated under section 1(7) of the [1964 c. 29.] Continental Shelf Act 1964, except an area or part of an area in which the law of Northern Ireland applies.
(6)An Order in Council under subsection (5) may provide that, in relation to employment to which the Order applies, this Part and section 1 of the [1970 c. 41.] Equal Pay Act 1970 are to have effect with such modifications as are specified in the Order.
(7)An Order in Council under subsection (5) shall be of no effect unless a draft of the Order was laid before and approved by each House of Parliament.