6.—(1) Exemption from designation under section 23(1) of the Act (designation of passenger services as eligible for franchising) is granted to any person who provides—
(a)a railway passenger service which was, immediately before the coming into force of this article, provided other than by a person falling within any of sub-paragraphs (i) to (iv) of article 4(a);
(b)a railway passenger service (other than a service falling within sub-paragraph (a) above) provided wholly on a railway line or railway lines comprised in a specified network; or
(c)a railway passenger service (other than a service falling within sub-paragraph (b) above) which involves travel through the Channel Tunnel;
in respect of that service.
(2) So far as it relates to any particular railway passenger service, the exemption granted in this article may be revoked by agreement in writing between the Secretary of State and the person providing that service.