For the purposes of this Chapter a person shall be taken to have significant market power in relation to a market if he enjoys a position which amounts to or is equivalent to dominance of the market.

References in this section to dominance of a market are to be construed, so far as it is appropriate to do so for the purposes of this Chapter, in the same way as the reference in section 18(1) of the Competition Act 1998 to a dominant position in a market.

A person is to be taken to enjoy a position of dominance of a market if he is one of a number of persons who enjoy such a position in combination with each other.

A person or combination of persons may also be taken to enjoy a position of dominance of a market by reason wholly or partly of his or their position in a closely related market if the links between the two markets allow the market power held in the closely related market to be used in a way that influences the other market so as to strengthen the position in the other market of that person or combination of persons.

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