The Industry Act (1975) gives the Secretary of State for Trade and Industry the powers necessary to prohibit a proposed transfer of control of an important UK manufacturing undertaking to a non-resident where the transfer is considered contrary to the interests of the UK or a substantial part of it.  For these purposes “the national interest” means the national interest in relation to public policy, public security or public health. If it is considered that the national interest cannot appropriately be protected in any other way, property in such a proposal or completed transfer may be compulsorily acquired against compensation. Both prohibition and vesting orders are subject to Parliamentary approval.
"Part II - Powers in relation to Transfers of Control of Important Manufacturing Undertakings to Non-Residents
 11 General extent of powers in relation to control of important manufacturing undertakings.
(1)The powers conferred by this Part of this Act shall have effect in relation to changes of control of important manufacturing undertakings.
(2)In this Part of this Act—
“important manufacturing undertaking” means an undertaking which, in so far as it is carried on in the United Kingdom, is wholly or mainly engaged in manufacturing industry and appears to the Secretary of State to be of special importance to the United Kingdom or to any substantial part of the United Kingdom.
12 Meaning of “change of control”.
(1)There is a change of control of an important manufacturing undertaking for the purposes of this Part of this Act only upon the happening of a relevant event.
(2)In subsection (1) above “relevant event” means any event as a result of which—
(a)the person carrying on the whole or part of the undertaking ceases to be resident in the United Kingdom;
(b)a person not resident in the United Kingdom acquires the whole or part of the undertaking;
(c)a body corporate resident in the United Kingdom but controlled by a person not so resident acquires the whole or part of the undertaking;
(d)a person not resident in the United Kingdom becomes able to exercise or control the exercise of the first, second or third qualifying percentage of votes in a body corporate carrying on the whole or part of the undertaking or in any other body corporate which is in control of such a body; or
(e)a person resident in the United Kingdom and able to exercise or control the exercise of the first, second or third qualifying percentage of votes in a body corporate carrying on the whole or part of the undertaking or in any other body corporate which is in control of such a body ceases to be resident in the United Kingdom.
(3)For the purposes of subsection (2) above—
(a)a body corporate or individual entitled to cast 30 per cent. or more of the votes that may be cast at any general meeting of a body corporate is in control of that body; and
(b)control of a body corporate which has control of another body corporate gives control of the latter body.
(4)Any power to direct the holder of shares or stock in a body corporate as to the exercise of his votes at a general meeting of that body corporate is to be treated as entitlement to cast the votes in respect of the shares or stock in question.
(5)Two or more persons acting together in concert may be treated as a single person for the purposes of any provision of this Part of this Act relating to change of control.
(6)For the purposes of this Part of this Act—
(a)the first qualifying percentage of votes is 30 per cent.;
(b)the second qualifying percentage is 40 per cent.; and
(c)the third qualifying percentage is 50 per cent.;and the references to votes in this subsection are references to votes that may be cast at a general meeting.
13 Power to make orders.
(1)If it appears to the Secretary of State—
(a)that there is a serious and immediate probability of a change of control of an important manufacturing undertaking; and
(b)that that change of control would be contrary to the interests of the United Kingdom, or contrary to the interests of any substantial part of the United Kingdom,he may by order (in this Part of this Act referred to as a “prohibition order”) specify the undertaking and—
(i)prohibit that change of control; and
(ii)prohibit or restrict the doing of things which in his opinion would constitute or lead to it;and may make such incidental or supplementary provision in the order as appears to him to be necessary or expedient.
(2)Subject to subsection (3) below, if—
(a)the conditions specified in paragraphs (a) and (b) of subsection (1) above are satisfied, or
(b)a prohibition order has been made in relation to an important manufacturing undertaking, or
(c)the Secretary of State has learnt of circumstances which appear to him to constitute a change of control of an important manufacturing undertaking, occurring on or after 1st February 1975, and is satisfied that that change is contrary to the interests of the United Kingdom, or contrary to the interests of any substantial part of the United Kingdom,the Secretary of State may by order made with the approval of the Treasury (in this Part of this Act referred to as a “vesting order”) direct that on a day specified in the order—
(i)share capital and loan capital to which this subsection applies, or
(ii)any assets which are employed in the undertaking,shall vest in . . . in himself or in nominees for  . . . himself and may make such incidental or supplementary provision in the order as appears to him to be necessary or expedient.
(3)A vesting order may only be made if the Secretary of State is satisfied that the order is necessary in the national interest and that, having regard to all the circumstances, that interest cannot, or cannot appropriately, be protected in any other way.
(4)The share capital and loan capital to which subsection (2) above applies are—
(a)in any case where the Secretary of State considers that the interests mentioned in subsection (2)(c) above cannot, or cannot appropriately, be protected unless all the share capital of any relevant body corporate vests by virtue of the order, the share capital of that body corporate, together with so much (if any) of the loan capital of that body as may be specified in the order,
(b)in any other case, that part of the share capital of any relevant body corporate which, at the time that the draft of the order is laid before Parliament under section 15(3) below, appears to the Secretary of State to be involved in the change of control.
(5)In this section “relevant body corporate” means—
(a)a body corporate incorporated in the United Kingdom carrying on in the United Kingdom as the whole or the major part of its business there the whole or part of an important manufacturing undertaking, or
(b)a body corporate incorporated in the United Kingdom—
(i)which is the holding company of a group of companies carrying on in the United Kingdom as the whole or the major part of their business there the whole or part of an important manufacturing undertaking, and
(ii)as to which one of the conditions specified in subsection (6) below is satisfied.
(6)The conditions mentioned in subsection (5) above are—
(a)that it appears to the Secretary of State that there is a serious and immediate probability of the happening of an event in relation to the company which would constitute a change of control of the undertaking, or
(b)that the Secretary of State has learnt of circumstances relating to the company which appear to him to constitute a change of control of the undertaking on or after 1st February 1975.
[(7)In sections (1)(b) and (2)(c) “interests” means interests which relate to public policy, public security or public health.
(8)In subsection (3) “the national interest” means the national interest in relation to public policy, public security or public health.][...]" (Industry Act 1975 (UKPGA 1975 c. 68), last amended on 1.10.2008, Sections 11, 12 and 13)
Industry Act 1975 (UKPGA 1975 c. 68), last amended on 1.10.2008, Sections 11, 12 and 13
[<a href="https://www.legislation.gov.uk/ukpga/1975/68/introduction">Industry Act 1975</a>]