The following is the NGK UK Website which list the appropriate Spark Plug for several different engines fitted to 7's:-
http://www.ngkpartfinder.co.uk/car_commercial_search.php?type=SPARK%2520...
Sorry, but the full text of this page is only available to users with a membership.
If you are already a full member please log in to your account and ensure your membership details are correctly entered into your user account.
If you have registered on the website, but have not yet paid for full membership - you can do that here.