Where a person who has no pension rights under an established scheme enters before the 1st January 1969 the employment of a new authority or of the freightliner company or the freight-sundries company after leaving the employment of the Railways Board, the Holding company or a subsidiary of that Board or Company, he shall be eligible to become a member of that established scheme to the same extent and on the same basis as he would have been so eligible if, instead of entering the employment of that new authority or company, he had been continuing in comparable employment of the Railways Board, the Holding Company or the subsidiary of that Board or Company (as the case may be).