Valentine, Jvalentine, Jwood, L2012-04-242012-04-242006-122006-12The National Grid #2, pp.8 - 19.1177-2468https://hdl.handle.net/10292/4000No abstract© The National Grid, authors, 2006. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means without prior permission in writing from the publishers.Journal ArticleOpenAccess