Dang! Must not have got the getMostWatchedItems response!
Call used was: http://svcs.ebay.com/MerchandisingService?OPERATION-NAME=getMostWatchedItems&SERVICE-VERSION=1.0.0&CONSUMER-ID=SkyTechE-5d6d-452d-b0d6-ca538ed4e104&RESPONSE-DATA-FORMAT=XML&networkId=9&trackingId=5336847264&maxResults=5&categoryId=73