Paragraph 18

The undertaker shall indemnify Railtrack from and against all claims and demands arising out of or in connection with the specified works and the fact that any act or thing may have been done by Railtrack on behalf of the undertaker or in accordance with plans approved by the engineer or in accordance with any requirement of the engineer or under his supervision shall not (if it was done without negligence on the part of Railtrack or of any person in its employ or of its contractors or agents) excuse the undertaker from any liability under the provisions of this paragraph.