TFS Subscriber example, need to access WorkItemStore

gistfile1.cs

   public EventNotificationStatus ProcessEvent(
            TeamFoundationRequestContext requestContext,
            NotificationType notificationType,
            object notificationEventArgs,
            out int statusCode,
            out string statusMessage,
            out ExceptionPropertyCollection properties
            )
        {
            statusCode = 0;
            statusMessage = string.Empty;
            properties = null;
            
            if (notificationType == NotificationType.Notification && notificationEventArgs is WorkItemChangedEvent)
            {
                WorkItemChangedEvent data = notificationEventArgs as WorkItemChangedEvent;

                // I now have access to the CoreFields and TextFields via WorkItemChangedEvent
                // but I want to access other fields in the work item. It seems the only way to do
                // this is to load the WorkItem from the WorkItemStore in full.

                // Although I can connect to the WorkItemStore using the WorkItemTracking.Client
                // methods this seems messy, and I'd have to construct the URL from 
                // TeamFoundationRequestContext - SURELY there a way to access the WorkItemStore
                // using the existing context (TeamFoundationRequestContext)?
            }

            return EventNotificationStatus.ActionPermitted;
        }